Poj 1200 Crazy Search [hash]

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Question:

Given N, NC, and a string, this string is composed of NC characters. Now you need to find the number of types of sub-strings with the length of N in this string.

Solution Analysis:

To judge the weight, hash these strings and map different strings to numbers. Here we convert the string to the NC hexadecimal number, different strings correspond to different numbers in NC.

 1 # Include <cstdio>2 # Include <cstring> 3   Using   Namespace  STD;  4   Const   Int M = 16e6 + 10  ;  5   Char  STR [m];  6   Bool  Hash [m];  7  Int Cur [ 256  ];  8   9   Int  Main (){  10       Int  N, NC;  11       While (Scanf ( "  % D % s  " , & N, & NC, STR )! = EOF ){ 12           Int CNT = 0  ;  13 Memset (cur, 0 , Sizeof  (Cur ));  14 Memset (hash, False , Sizeof  (Hash ));  15           Int Len = Strlen (STR ); 16           For ( Int I = 0 ; I <Len; I ++ ){ //  Assign numbers to all characters  17               If (! Cur [STR [I])  18 Cur [STR [I] = ++ CNT;  19               If (CNT = NC) Break  ; 20   }  21           Int Ans = 0  ;  22           For ( Int I = 0 ; I + N- 1 <Len; I ++ ){  23               Int Sum = 0  ; 24               For ( Int J = I; j <I + N; j ++ ){  25 Sum + = sum * nC + cur [STR [J]; //  Returns the value of this string converted to the NC hexadecimal number.  26   }  27               If (! Hash [Sum]) {  28 ++ Ans;  29 Hash [Sum] = True  ;  30   }  31   }  32 Printf ( "  % D \ n  "  , ANS );  33   }  34       Return   0 ;  35 }

 

 

Poj 1200 Crazy Search [hash]