bzoj 3555 企鹅QQ

https://www.lydsy.com/JudgeOnline/problem.php?id=3555

枚举每一位字符，计算字符两侧的哈希值，然后进行比较，用map或排序记录出与其相同的字符串数量。

时间复杂度O(nlog_n)

#include <algorithm>
#include <iostream>
#include <cstring>
#include <cstdio>
#include <cstdio>
using namespace std;
#define LL long long
#define N int(3e4+2)
#define M int(2e2+2)
#define base1 233
#define base2 211
int n,m,l,ans;
char s[M];
unsigned long long temp[N],before[N][M],behind[N][M];
void work(int x)
{
    for(int i=;i<=l;i++)before[x][i]=before[x][i-]*+s[i];
    for(int i=l;i>=;i--)behind[x][i]=behind[x][i+]*+s[i];
}
int main()
{
    scanf("%d%d%d",&n,&l,&m);
    for(int i=;i<=n;i++)
    {
        scanf("%s",s+);
        work(i);
    }
    for(int j=;j<=l;j++)
    {
        for(int i=;i<=n;i++)temp[i]=before[i][j-]*+behind[i][j+]*;
        sort(temp+,temp++n);
        int now=;
        for(int i=;i<=n;i++)
        {
            if(temp[i]==temp[i-])ans+=now,now++;
            else now=;
        }
    }
    printf("%d",ans);
}