poj 1200 Crazy Search

#include <stdio.h>
#include <string.h>

const int N = 1000000;
const int MAX_N = 16000000;
int hash[MAX_N];
char A[N];
int value[128];

int main( )
{
    int N, NC, hashVal, valueKey = 0;
    int len, ans = 0, Count = 0;

    memset( value, 0, sizeof( value ) );
    memset( A, 0, sizeof( A ) );
    memset( hash, 0, sizeof( hash ) );
    scanf( "%d %d\n", &N, &NC );
    scanf( "%s", A );

    len = strlen( A );
    for ( int i = 0; i < len; ++i )
    {
        if ( value[A[i]] == 0 )
            value[A[i]] = ++valueKey;

        if ( valueKey == NC )
            break;
    }

    for ( int i = 0; i + N <= len; ++i )
    {
        hashVal = 0;
        for ( int j = i; j < i + N; ++j )
            hashVal = hashVal * NC + value[A[j]] - 1;
        if ( hash[hashVal] == 0 )
        {
            hash[hashVal] = 1;
            ans++;
        }
    }

    printf( "%d\n", ans );
    return 0;
}