{"id":477431,"date":"2023-08-09T09:14:50","date_gmt":"2023-08-09T09:14:50","guid":{"rendered":""},"modified":"2023-09-05T11:14:42","modified_gmt":"2023-09-05T11:14:42","slug":"hash-table","status":"publish","type":"wiki","link":"https:\/\/oneproxy.pro\/vn\/wiki\/hash-table\/","title":{"rendered":"B\u1ea3ng b\u0103m"},"content":{"rendered":"

B\u1ea3ng b\u0103m, c\u00f2n \u0111\u01b0\u1ee3c g\u1ecdi l\u00e0 b\u1ea3n \u0111\u1ed3 b\u0103m, l\u00e0 m\u1ed9t c\u1ea5u tr\u00fac d\u1eef li\u1ec7u ph\u1ee9c t\u1ea1p cho ph\u00e9p l\u01b0u tr\u1eef v\u00e0 truy xu\u1ea5t d\u1eef li\u1ec7u nhanh ch\u00f3ng. N\u00f3 th\u1ef1c hi\u1ec7n \u0111i\u1ec1u n\u00e0y b\u1eb1ng c\u00e1ch li\u00ean k\u1ebft c\u00e1c kh\u00f3a v\u1edbi c\u00e1c gi\u00e1 tr\u1ecb c\u1ee5 th\u1ec3, s\u1eed d\u1ee5ng m\u1ed9t quy tr\u00ecnh duy nh\u1ea5t \u0111\u01b0\u1ee3c g\u1ecdi l\u00e0 \u201cb\u0103m\u201d.<\/p>\n

Ngu\u1ed3n g\u1ed1c c\u1ee7a b\u1ea3ng b\u0103m<\/h2>\n

B\u1ea3ng b\u0103m b\u1eaft ngu\u1ed3n t\u1eeb nhu c\u1ea7u v\u1ec1 c\u00e1c ph\u01b0\u01a1ng ph\u00e1p truy xu\u1ea5t d\u1eef li\u1ec7u nhanh h\u01a1n trong khoa h\u1ecdc m\u00e1y t\u00ednh. Ch\u00fang \u0111\u01b0\u1ee3c m\u00f4 t\u1ea3 l\u1ea7n \u0111\u1ea7u ti\u00ean trong t\u00e0i li\u1ec7u v\u00e0o n\u0103m 1953 trong m\u1ed9t b\u1ea3n ghi nh\u1edb \u0111\u01b0\u1ee3c vi\u1ebft b\u1edfi HP Luhn, m\u1ed9t nh\u00e0 nghi\u00ean c\u1ee9u c\u1ee7a IBM. Luhn \u0111\u00e3 gi\u1edbi thi\u1ec7u h\u00e0m b\u0103m v\u00e0 th\u1ea3o lu\u1eadn v\u1ec1 kh\u1ea3 n\u0103ng tri\u1ec3n khai b\u1ea3ng b\u0103m \u0111\u1ec3 truy c\u1eadp d\u1eef li\u1ec7u nhanh ch\u00f3ng. Tuy nhi\u00ean, vi\u1ec7c tri\u1ec3n khai th\u1ef1c t\u1ebf b\u1ea3ng b\u0103m ch\u1ec9 b\u1eaft \u0111\u1ea7u v\u00e0o cu\u1ed1i nh\u1eefng n\u0103m 1960 v\u00e0 \u0111\u1ea7u nh\u1eefng n\u0103m 1970. K\u1ec3 t\u1eeb \u0111\u00f3, ch\u00fang \u0111\u00e3 tr\u1edf th\u00e0nh nh\u1eefng th\u00e0nh ph\u1ea7n thi\u1ebft y\u1ebfu trong nhi\u1ec1u \u1ee9ng d\u1ee5ng m\u00e1y t\u00ednh kh\u00e1c nhau do t\u00ednh ph\u1ee9c t\u1ea1p v\u01b0\u1ee3t tr\u1ed9i v\u1ec1 m\u1eb7t th\u1eddi gian trong c\u00e1c ho\u1ea1t \u0111\u1ed9ng t\u00ecm ki\u1ebfm.<\/p>\n

\u0110i s\u00e2u h\u01a1n v\u00e0o b\u1ea3ng b\u0103m<\/h2>\n

B\u1ea3ng b\u0103m s\u1eafp x\u1ebfp d\u1eef li\u1ec7u \u0111\u1ec3 tra c\u1ee9u nhanh c\u00e1c gi\u00e1 tr\u1ecb, ch\u1eb3ng h\u1ea1n nh\u01b0 danh b\u1ea1 \u0111i\u1ec7n tho\u1ea1i n\u01a1i ng\u01b0\u1eddi ta c\u00f3 th\u1ec3 tra c\u1ee9u t\u00ean c\u1ee7a m\u1ed9t ng\u01b0\u1eddi (\u201cch\u00eca kh\u00f3a\u201d) \u0111\u1ec3 t\u00ecm s\u1ed1 \u0111i\u1ec7n tho\u1ea1i c\u1ee7a h\u1ecd (\u201cgi\u00e1 tr\u1ecb\u201d). Nguy\u00ean t\u1eafc c\u01a1 b\u1ea3n c\u1ee7a b\u1ea3ng b\u0103m l\u00e0 m\u1ed9t h\u00e0m \u0111\u1eb7c bi\u1ec7t \u0111\u01b0\u1ee3c g\u1ecdi l\u00e0 \u201ch\u00e0m b\u0103m\u201d. H\u00e0m n\u00e0y l\u1ea5y \u0111\u1ea7u v\u00e0o (ho\u1eb7c 'kh\u00f3a') v\u00e0 tr\u1ea3 v\u1ec1 m\u1ed9t s\u1ed1 nguy\u00ean, sau \u0111\u00f3 c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng l\u00e0m ch\u1ec9 m\u1ee5c \u0111\u1ec3 l\u01b0u tr\u1eef gi\u00e1 tr\u1ecb li\u00ean quan.<\/p>\n

H\u00e0m b\u0103m nh\u1eb1m m\u1ee5c \u0111\u00edch ph\u00e2n ph\u1ed1i c\u00e1c kh\u00f3a \u0111\u1ed3ng \u0111\u1ec1u tr\u00ean m\u1ed9t t\u1eadp h\u1ee3p c\u00e1c nh\u00f3m ho\u1eb7c v\u1ecb tr\u00ed x\u00e1c \u0111\u1ecbnh, gi\u1ea3m thi\u1ec3u kh\u1ea3 n\u0103ng xung \u0111\u1ed9t (trong \u0111\u00f3 hai kh\u00f3a kh\u00e1c nhau \u00e1nh x\u1ea1 t\u1edbi c\u00f9ng m\u1ed9t v\u1ecb tr\u00ed). Tuy nhi\u00ean, khi xung \u0111\u1ed9t x\u1ea3y ra, ch\u00fang c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c x\u1eed l\u00fd theo nhi\u1ec1u c\u00e1ch kh\u00e1c nhau, ch\u1eb3ng h\u1ea1n nh\u01b0 \u201cchu\u1ed7i\u201d (n\u01a1i c\u00e1c ph\u1ea7n t\u1eed xung \u0111\u1ed9t \u0111\u01b0\u1ee3c l\u01b0u tr\u1eef trong danh s\u00e1ch li\u00ean k\u1ebft) ho\u1eb7c \u201c\u0111\u1ecba ch\u1ec9 m\u1edf\u201d (n\u01a1i t\u00ecm ki\u1ebfm c\u00e1c v\u1ecb tr\u00ed thay th\u1ebf).<\/p>\n

C\u1ea5u tr\u00fac b\u00ean trong c\u1ee7a b\u1ea3ng b\u0103m v\u00e0 c\u00e1ch ch\u00fang ho\u1ea1t \u0111\u1ed9ng<\/h2>\n

C\u00e1c th\u00e0nh ph\u1ea7n ch\u00ednh c\u1ee7a b\u1ea3ng b\u0103m bao g\u1ed3m:<\/p>\n

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  1. \n

    Ph\u00edm<\/strong>: \u0110\u00e2y l\u00e0 nh\u1eefng m\u00e3 \u0111\u1ecbnh danh duy nh\u1ea5t \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng \u0111\u1ec3 \u00e1nh x\u1ea1 c\u00e1c gi\u00e1 tr\u1ecb li\u00ean quan.<\/p>\n<\/li>\n

  2. \n

    H\u00e0m b\u0103m<\/strong>: \u0110\u00e2y l\u00e0 h\u00e0m t\u00ednh to\u00e1n ch\u1ec9 m\u1ee5c d\u1ef1a tr\u00ean kh\u00f3a v\u00e0 k\u00edch th\u01b0\u1edbc hi\u1ec7n t\u1ea1i c\u1ee7a b\u1ea3ng b\u0103m.<\/p>\n<\/li>\n

  3. \n

    X\u00f4 ho\u1eb7c Khe<\/strong>: \u0110\u00e2y l\u00e0 nh\u1eefng v\u1ecb tr\u00ed l\u01b0u tr\u1eef c\u00e1c gi\u00e1 tr\u1ecb li\u00ean quan \u0111\u1ebfn kh\u00f3a.<\/p>\n<\/li>\n

  4. \n

    Gi\u00e1 tr\u1ecb<\/strong>: \u0110\u00e2y l\u00e0 nh\u1eefng d\u1eef li\u1ec7u th\u1ef1c t\u1ebf c\u1ea7n \u0111\u01b0\u1ee3c l\u01b0u tr\u1eef v\u00e0 truy xu\u1ea5t.<\/p>\n<\/li>\n<\/ol>\n

    M\u1ed9t kh\u00f3a \u0111\u01b0\u1ee3c \u0111\u01b0a v\u00e0o h\u00e0m b\u0103m, sau \u0111\u00f3 t\u1ea1o ra m\u1ed9t s\u1ed1 nguy\u00ean. S\u1ed1 nguy\u00ean n\u00e0y \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng l\u00e0m ch\u1ec9 m\u1ee5c \u0111\u1ec3 l\u01b0u tr\u1eef gi\u00e1 tr\u1ecb trong b\u1ea3ng b\u0103m. Khi c\u1ea7n l\u1ea5y gi\u00e1 tr\u1ecb, kh\u00f3a t\u01b0\u01a1ng t\u1ef1 s\u1ebd \u0111\u01b0\u1ee3c b\u0103m l\u1ea1i \u0111\u1ec3 t\u1ea1o s\u1ed1 nguy\u00ean. S\u1ed1 nguy\u00ean n\u00e0y sau \u0111\u00f3 \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng l\u00e0m ch\u1ec9 m\u1ee5c \u0111\u1ec3 l\u1ea5y gi\u00e1 tr\u1ecb. T\u1ed1c \u0111\u1ed9 c\u1ee7a qu\u00e1 tr\u00ecnh n\u00e0y l\u00e0 l\u00fd do t\u1ea1i sao b\u1ea3ng b\u0103m l\u1ea1i r\u1ea5t hi\u1ec7u qu\u1ea3 trong vi\u1ec7c tra c\u1ee9u d\u1eef li\u1ec7u.<\/p>\n

    C\u00e1c t\u00ednh n\u0103ng ch\u00ednh c\u1ee7a b\u1ea3ng b\u0103m<\/h2>\n

    B\u1ea3ng b\u0103m l\u00e0 c\u1ea5u tr\u00fac d\u1eef li\u1ec7u c\u1ef1c k\u1ef3 hi\u1ec7u qu\u1ea3 v\u00e0 linh ho\u1ea1t. D\u01b0\u1edbi \u0111\u00e2y l\u00e0 m\u1ed9t s\u1ed1 t\u00ednh n\u0103ng ch\u00ednh c\u1ee7a h\u1ecd:<\/p>\n

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    1. \n

      T\u1ed1c \u0111\u1ed9<\/strong>: B\u1ea3ng b\u0103m c\u00f3 \u0111\u1ed9 ph\u1ee9c t\u1ea1p v\u1ec1 th\u1eddi gian trung b\u00ecnh l\u00e0 O(1) cho c\u00e1c thao t\u00e1c t\u00ecm ki\u1ebfm, ch\u00e8n v\u00e0 x\u00f3a, khi\u1ebfn ch\u00fang tr\u1edf n\u00ean l\u00fd t\u01b0\u1edfng \u0111\u1ec3 truy xu\u1ea5t d\u1eef li\u1ec7u nhanh ch\u00f3ng.<\/p>\n<\/li>\n

    2. \n

      L\u01b0u tr\u1eef hi\u1ec7u qu\u1ea3<\/strong>: B\u1ea3ng b\u0103m s\u1eed d\u1ee5ng c\u1ea5u tr\u00fac gi\u1ed1ng m\u1ea3ng \u0111\u1ec3 l\u01b0u tr\u1eef d\u1eef li\u1ec7u, r\u1ea5t ti\u1ebft ki\u1ec7m kh\u00f4ng gian.<\/p>\n<\/li>\n

    3. \n

      Ph\u00edm linh ho\u1ea1t<\/strong>: C\u00e1c kh\u00f3a trong b\u1ea3ng b\u0103m kh\u00f4ng c\u1ea7n ph\u1ea3i l\u00e0 s\u1ed1 nguy\u00ean. Ch\u00fang c\u00f3 th\u1ec3 l\u00e0 c\u00e1c ki\u1ec3u d\u1eef li\u1ec7u kh\u00e1c nh\u01b0 chu\u1ed7i ho\u1eb7c \u0111\u1ed1i t\u01b0\u1ee3ng.<\/p>\n<\/li>\n

    4. \n

      X\u1eed l\u00fd va ch\u1ea1m<\/strong>: B\u1ea3ng b\u0103m x\u1eed l\u00fd xung \u0111\u1ed9t th\u00f4ng qua m\u1ed9t s\u1ed1 ph\u01b0\u01a1ng ph\u00e1p nh\u01b0 x\u00e2u chu\u1ed7i ho\u1eb7c \u0111\u00e1nh \u0111\u1ecba ch\u1ec9 m\u1edf.<\/p>\n<\/li>\n<\/ol>\n

      C\u00e1c lo\u1ea1i b\u1ea3ng b\u0103m<\/h2>\n

      C\u00f3 m\u1ed9t s\u1ed1 lo\u1ea1i b\u1ea3ng b\u0103m, \u0111\u01b0\u1ee3c ph\u00e2n bi\u1ec7t ch\u1ee7 y\u1ebfu b\u1eb1ng c\u00e1ch ch\u00fang x\u1eed l\u00fd c\u00e1c xung \u0111\u1ed9t:<\/p>\n

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      1. \n

        B\u1ea3ng b\u0103m chu\u1ed7i ri\u00eang bi\u1ec7t<\/strong>: C\u00e1i n\u00e0y s\u1eed d\u1ee5ng danh s\u00e1ch li\u00ean k\u1ebft \u0111\u1ec3 l\u01b0u tr\u1eef c\u00e1c kh\u00f3a b\u0103m theo c\u00f9ng m\u1ed9t ch\u1ec9 m\u1ee5c.<\/p>\n<\/li>\n

      2. \n

        M\u1edf b\u1ea3ng b\u0103m \u0111\u1ecba ch\u1ec9 (Th\u0103m d\u00f2 tuy\u1ebfn t\u00ednh)<\/strong>: N\u1ebfu x\u1ea3y ra xung \u0111\u1ed9t, ph\u01b0\u01a1ng ph\u00e1p n\u00e0y s\u1ebd t\u00ecm v\u1ecb tr\u00ed c\u00f3 s\u1eb5n ti\u1ebfp theo ho\u1eb7c th\u1eed l\u1ea1i v\u1ecb tr\u00ed hi\u1ec7n t\u1ea1i.<\/p>\n<\/li>\n

      3. \n

        B\u1ea3ng b\u0103m \u0111\u00f4i<\/strong>: M\u1ed9t d\u1ea1ng \u0111\u1ecba ch\u1ec9 m\u1edf s\u1eed d\u1ee5ng h\u00e0m b\u0103m th\u1ee9 hai \u0111\u1ec3 t\u00ecm m\u1ed9t khe tr\u1ed1ng trong tr\u01b0\u1eddng h\u1ee3p x\u1ea3y ra xung \u0111\u1ed9t.<\/p>\n<\/li>\n

      4. \n

        B\u0103m c\u00fac cu<\/strong>: S\u1eed d\u1ee5ng hai h\u00e0m b\u0103m thay v\u00ec m\u1ed9t. Khi m\u1ed9t kh\u00f3a m\u1edbi va ch\u1ea1m v\u1edbi m\u1ed9t kh\u00f3a hi\u1ec7n c\u00f3, kh\u00f3a c\u0169 s\u1ebd \u0111\u01b0\u1ee3c chuy\u1ec3n sang v\u1ecb tr\u00ed m\u1edbi.<\/p>\n<\/li>\n

      5. \n

        B\u0103m l\u00f2 c\u00f2<\/strong>: M\u1ed9t ph\u1ea7n m\u1edf r\u1ed9ng c\u1ee7a th\u0103m d\u00f2 tuy\u1ebfn t\u00ednh v\u00e0 cung c\u1ea5p m\u1ed9t c\u00e1ch hi\u1ec7u qu\u1ea3 \u0111\u1ec3 x\u1eed l\u00fd h\u1ec7 s\u1ed1 t\u1ea3i cao v\u00e0 hi\u1ec7u su\u1ea5t b\u1ed9 \u0111\u1ec7m t\u1ed1t.<\/p>\n<\/li>\n<\/ol>\n

        \u1ee8ng d\u1ee5ng c\u1ee7a B\u1ea3ng b\u0103m, Th\u1eed th\u00e1ch v\u00e0 Gi\u1ea3i ph\u00e1p<\/h2>\n

        B\u1ea3ng b\u0103m \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng r\u1ed9ng r\u00e3i trong nhi\u1ec1u l\u0129nh v\u1ef1c, bao g\u1ed3m l\u1eadp ch\u1ec9 m\u1ee5c c\u01a1 s\u1edf d\u1eef li\u1ec7u, b\u1ed9 nh\u1edb \u0111\u1ec7m, l\u01b0u tr\u1eef m\u1eadt kh\u1ea9u cho c\u00e1c \u1ee9ng d\u1ee5ng web, v.v. B\u1ea5t ch\u1ea5p ti\u1ec7n \u00edch c\u1ee7a ch\u00fang, nh\u1eefng th\u00e1ch th\u1ee9c c\u00f3 th\u1ec3 n\u1ea3y sinh t\u1eeb vi\u1ec7c s\u1eed d\u1ee5ng b\u1ea3ng b\u0103m. V\u00ed d\u1ee5: vi\u1ec7c l\u1ef1a ch\u1ecdn h\u00e0m b\u0103m k\u00e9m c\u00f3 th\u1ec3 d\u1eabn \u0111\u1ebfn ph\u00e2n c\u1ee5m, l\u00e0m gi\u1ea3m hi\u1ec7u qu\u1ea3 c\u1ee7a b\u1ea3ng b\u0103m. Ngo\u00e0i ra, vi\u1ec7c x\u1eed l\u00fd c\u00e1c va ch\u1ea1m c\u0169ng c\u00f3 th\u1ec3 \u0111\u00f2i h\u1ecfi nhi\u1ec1u t\u00ednh to\u00e1n.<\/p>\n

        Vi\u1ec7c l\u1ef1a ch\u1ecdn c\u00e1c h\u00e0m b\u0103m t\u1ed1t, ph\u00e2n ph\u1ed1i c\u00e1c kh\u00f3a \u0111\u1ed3ng \u0111\u1ec1u tr\u00ean b\u1ea3ng b\u0103m, c\u00f3 th\u1ec3 gi\u1ea3m thi\u1ec3u vi\u1ec7c ph\u00e2n c\u1ee5m. \u0110\u1ec3 x\u1eed l\u00fd xung \u0111\u1ed9t, c\u00e1c ph\u01b0\u01a1ng ph\u00e1p nh\u01b0 \u0111\u00e1nh \u0111\u1ecba ch\u1ec9 m\u1edf ho\u1eb7c x\u00e2u chu\u1ed7i \u0111\u1ec1u c\u00f3 hi\u1ec7u qu\u1ea3. Ngo\u00e0i ra, vi\u1ec7c thay \u0111\u1ed5i k\u00edch th\u01b0\u1edbc \u0111\u1ed9ng c\u1ee7a b\u1ea3ng b\u0103m c\u00f3 th\u1ec3 ng\u0103n ch\u1eb7n t\u00ecnh tr\u1ea1ng suy gi\u1ea3m hi\u1ec7u su\u1ea5t do h\u1ec7 s\u1ed1 t\u1ea3i cao.<\/p>\n

        So s\u00e1nh v\u1edbi c\u00e1c c\u1ea5u tr\u00fac d\u1eef li\u1ec7u kh\u00e1c<\/h2>\n\n\n\n\n\n\n\n
        C\u1ea5u tr\u00fac d\u1eef li\u1ec7u<\/th>\n\u0110\u1ed9 ph\u1ee9c t\u1ea1p th\u1eddi gian trung b\u00ecnh cho t\u00ecm ki\u1ebfm<\/th>\n\u0110\u1ed9 ph\u1ee9c t\u1ea1p c\u1ee7a kh\u00f4ng gian<\/th>\n<\/tr>\n<\/thead>\n
        B\u1ea3ng b\u0103m<\/td>\nO(1)<\/td>\nTR\u00caN)<\/td>\n<\/tr>\n
        C\u00e2y t\u00ecm ki\u1ebfm nh\u1ecb ph\u00e2n<\/td>\nO(logn)<\/td>\nTR\u00caN)<\/td>\n<\/tr>\n
        L\u1eadp danh s\u00e1ch<\/td>\nTR\u00caN)<\/td>\nTR\u00caN)<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

        Quan \u0111i\u1ec3m t\u01b0\u01a1ng lai v\u00e0 c\u00f4ng ngh\u1ec7 li\u00ean quan \u0111\u1ebfn b\u1ea3ng b\u0103m<\/h2>\n

        B\u1ea3ng b\u0103m s\u1ebd ti\u1ebfp t\u1ee5c \u0111\u00f3ng vai tr\u00f2 thi\u1ebft y\u1ebfu trong c\u00e1c c\u00f4ng ngh\u1ec7 t\u01b0\u01a1ng lai do t\u00ednh hi\u1ec7u qu\u1ea3 v\u01b0\u1ee3t tr\u1ed9i c\u1ee7a ch\u00fang. C\u00e1c l\u0129nh v\u1ef1c ph\u00e1t tri\u1ec3n ti\u1ec1m n\u0103ng bao g\u1ed3m t\u1ed1i \u01b0u h\u00f3a h\u00e0m b\u0103m b\u1eb1ng thu\u1eadt to\u00e1n h\u1ecdc m\u00e1y v\u00e0 ph\u00e1t tri\u1ec3n c\u00e1c k\u1ef9 thu\u1eadt gi\u1ea3i quy\u1ebft xung \u0111\u1ed9t hi\u1ec7u qu\u1ea3 h\u01a1n. Ngo\u00e0i ra, \u1ee9ng d\u1ee5ng b\u1ea3ng b\u0103m trong c\u00e1c h\u1ec7 th\u1ed1ng ph\u00e2n t\u00e1n v\u00e0 \u0111i\u1ec7n to\u00e1n \u0111\u00e1m m\u00e2y s\u1ebd ti\u1ebfp t\u1ee5c ph\u00e1t tri\u1ec3n v\u00ec nh\u1eefng c\u00f4ng ngh\u1ec7 n\u00e0y y\u00eau c\u1ea7u c\u00e1c ph\u01b0\u01a1ng ph\u00e1p truy c\u1eadp d\u1eef li\u1ec7u hi\u1ec7u qu\u1ea3.<\/p>\n

        B\u1ea3ng b\u0103m v\u00e0 m\u00e1y ch\u1ee7 proxy<\/h2>\n

        M\u00e1y ch\u1ee7 proxy c\u00f3 th\u1ec3 h\u01b0\u1edfng l\u1ee3i t\u1eeb b\u1ea3ng b\u0103m trong vi\u1ec7c qu\u1ea3n l\u00fd k\u1ebft n\u1ed1i m\u00e1y kh\u00e1ch-m\u00e1y ch\u1ee7. V\u00ed d\u1ee5: m\u00e1y ch\u1ee7 proxy c\u00f3 th\u1ec3 s\u1eed d\u1ee5ng b\u1ea3ng b\u0103m \u0111\u1ec3 theo d\u00f5i c\u00e1c y\u00eau c\u1ea7u c\u1ee7a kh\u00e1ch h\u00e0ng, \u00e1nh x\u1ea1 \u0111\u1ecba ch\u1ec9 IP c\u1ee7a t\u1eebng kh\u00e1ch h\u00e0ng (kh\u00f3a) t\u1edbi m\u00e1y ch\u1ee7 \u0111\u01b0\u1ee3c li\u00ean k\u1ebft (gi\u00e1 tr\u1ecb). \u0110i\u1ec1u n\u00e0y \u0111\u1ea3m b\u1ea3o chuy\u1ec3n h\u01b0\u1edbng nhanh ch\u00f3ng c\u00e1c y\u00eau c\u1ea7u c\u1ee7a kh\u00e1ch h\u00e0ng v\u00e0 x\u1eed l\u00fd hi\u1ec7u qu\u1ea3 nhi\u1ec1u k\u1ebft n\u1ed1i \u0111\u1ed3ng th\u1eddi.<\/p>\n

        Li\u00ean k\u1ebft li\u00ean quan<\/h2>\n

        \u0110\u1ec3 bi\u1ebft th\u00eam th\u00f4ng tin v\u1ec1 b\u1ea3ng b\u0103m, h\u00e3y tham kh\u1ea3o c\u00e1c t\u00e0i nguy\u00ean sau:<\/p>\n

          \n
        1. B\u1ea3ng b\u0103m \u2013 Wikipedia<\/a><\/li>\n
        2. B\u1ea3ng b\u0103m \u2013 GeeksforGeeks<\/a><\/li>\n
        3. Gi\u1edbi thi\u1ec7u v\u1ec1 B\u1ea3ng b\u0103m \u2013 Khan Academy<\/a><\/li>\n<\/ol>","protected":false},"featured_media":468522,"menu_order":0,"template":"","meta":{"_acf_changed":false,"content-type":"","inline_featured_image":false,"footnotes":""},"class_list":["post-477431","wiki","type-wiki","status-publish","has-post-thumbnail","hentry"],"acf":{"faq_title":"Frequently Asked Questions about Hash Tables: The Cornerstone of Efficient Data Management<\/mark>","faq_items":[{"question":"What is a hash table?","answer":"

          A hash table, also known as a hash map, is a data structure that allows for fast storage and retrieval of data. This is accomplished by associating keys with specific values, using a unique process known as \"hashing\".<\/p>"},{"question":"Who first described the concept of a hash table?","answer":"

          The concept of a hash table was first described in 1953 in a memorandum written by H. P. Luhn, an IBM researcher. However, the actual implementation of hash tables began only in the late 1960s and early 1970s.<\/p>"},{"question":"How does a hash table work?","answer":"

          A key is passed into the hash function, which generates an integer. This integer is used as the index to store the value in the hash table. When retrieving the value, the same key is hashed again to generate the integer, which is used as the index to retrieve the value.<\/p>"},{"question":"What are the key features of hash tables?","answer":"

          Hash tables are characterized by their speed, efficient storage, flexibility in the types of keys, and methods for handling collisions. They have an average time complexity of O(1) for search, insert, and delete operations.<\/p>"},{"question":"How are collisions handled in a hash table?","answer":"

          Collisions in a hash table, which occur when two different keys map to the same slot, can be handled in several ways such as chaining (where colliding elements are stored in a linked list) or open addressing (where alternative slots are found).<\/p>"},{"question":"What are some types of hash tables?","answer":"

          There are several types of hash tables, distinguished primarily by how they handle collisions. These include Separate Chaining Hash Table, Open Addressing Hash Table (Linear Probing), Double Hashing Hash Table, Cuckoo Hashing, and Hopscotch Hashing.<\/p>"},{"question":"Where are hash tables used?","answer":"

          Hash tables are used in many fields, including database indexing, caching, password storage for web applications, and more.<\/p>"},{"question":"How do hash tables compare with other data structures?","answer":"

          Compared to other data structures, hash tables offer a superior average time complexity for search operations (O(1)) and efficient space complexity (O(n)).<\/p>"},{"question":"What future developments are expected in hash tables?","answer":"

          Future developments may include optimizing hash functions using machine learning algorithms, developing more effective collision resolution techniques, and growing applications in distributed systems and cloud computing.<\/p>"},{"question":"How can proxy servers benefit from hash tables?","answer":"

          Proxy servers can use hash tables to manage client-server connections. For instance, each client's IP address can be mapped (the key) to the associated server (the value). This enables quick redirection of client requests and efficient handling of multiple simultaneous connections.<\/p>"}]},"_links":{"self":[{"href":"https:\/\/oneproxy.pro\/vn\/wp-json\/wp\/v2\/wiki\/477431","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/oneproxy.pro\/vn\/wp-json\/wp\/v2\/wiki"}],"about":[{"href":"https:\/\/oneproxy.pro\/vn\/wp-json\/wp\/v2\/types\/wiki"}],"version-history":[{"count":0,"href":"https:\/\/oneproxy.pro\/vn\/wp-json\/wp\/v2\/wiki\/477431\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/oneproxy.pro\/vn\/wp-json\/wp\/v2\/media\/468522"}],"wp:attachment":[{"href":"https:\/\/oneproxy.pro\/vn\/wp-json\/wp\/v2\/media?parent=477431"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}