HD1686(hash)

HD1686(hash)

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#include<stdio.h>
#include<string.h>
#define N 1000006
typedef unsigned long long ull;
ull p[N], has[N], base = 131;
char t[N], w[N];
void init()
{
    p[0] = 1;
    for(int i = 1; i< N; i++)
        p[i] = p[i-1] * base;
}

ull calw(char s[])
{
    int len =  strlen(s);
    ull sum = 0;
    for(int i = len-1; i >=0; i--)
        sum = sum * base + s[i];
    return sum;
}

void calt(char s[], int len)
{
    has[len] = 0;
    for(int i = len-1; i >= 0; i--)
        has[i] = has[i+1] * base + s[i];
}

int main()
{
    int n, len1, len2, sum;
    ull tem1;
    scanf("%d", &n);
    init();
    while(n--)
    {
        sum = 0;
        scanf("%s %s", w, t);
        len1 = strlen(w);
        len2 = strlen(t);
        tem1 = calw(w);
        calt(t, len2);
        for(int i = 0; i <= len2 - len1; i++)
            if(tem1 == has[i] - has[i+len1] * p[len1])
                sum++;
        printf("%d\n", sum);
    }
    return 0;
}