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  • CodeForces

        假如两个区间的26的字母出现的位置集合分别是 A1,B1,A2,B2,....., 我们再能找到一个排列p[] 使得 A[i] = B[p[i]] ,那么就可以成功映射了。

        显然集合可以直接hash,排序一下hash值就可以判断是否匹配了。。。。

      

        虽然不知道为什么要卡19260817,但反正我是坚决不写双hash的,最后随便换了一个大模数(甚至都不是质数2333)然后就过了。。。

    Discription

    You are given a string s of length n consisting of lowercase English letters.

    For two given strings s and t, say S is the set of distinct characters of s and T is the set of distinct characters of t. The strings s and t are isomorphic if their lengths are equal and there is a one-to-one mapping (bijection) f between S and Tfor which f(si) = ti. Formally:

    1. f(si) = ti for any index i,
    2. for any character  there is exactly one character  that f(x) = y,
    3. for any character  there is exactly one character  that f(x) = y.

    For example, the strings "aababc" and "bbcbcz" are isomorphic. Also the strings "aaaww" and "wwwaa" are isomorphic. The following pairs of strings are not isomorphic: "aab" and "bbb", "test" and "best".

    You have to handle m queries characterized by three integers x, y, len (1 ≤ x, y ≤ n - len + 1). For each query check if two substrings s[x... x + len - 1] and s[y... y + len - 1] are isomorphic.

    Input

    The first line contains two space-separated integers n and m (1 ≤ n ≤ 2·1051 ≤ m ≤ 2·105) — the length of the string s and the number of queries.

    The second line contains string s consisting of n lowercase English letters.

    The following m lines contain a single query on each line: xiyi and leni (1 ≤ xi, yi ≤ n1 ≤ leni ≤ n - max(xi, yi) + 1) — the description of the pair of the substrings to check.

    Output

    For each query in a separate line print "YES" if substrings s[xi... xi + leni - 1] ands[yi... yi + leni - 1] are isomorphic and "NO" otherwise.

    Example

    Input
    7 4
    abacaba
    1 1 1
    1 4 2
    2 1 3
    2 4 3
    Output
    YES
    YES
    NO
    YES

    Note

    The queries in the example are following:

    1. substrings "a" and "a" are isomorphic: f(a) = a;
    2. substrings "ab" and "ca" are isomorphic: f(a) = cf(b) = a;
    3. substrings "bac" and "aba" are not isomorphic since f(b) and f(c) must be equal to a at same time;
    4. substrings "bac" and "cab" are isomorphic: f(b) = cf(a) = af(c) = b.
    #include<bits/stdc++.h>
    #define ll long long
    using namespace std;
    const int maxn=200005,ha=998244357,b=233;
    inline int add(int x,int y){ x+=y; return x>=ha?x-ha:x;}
    int H[maxn][26],ci[maxn],A[26],B[26];
    int n,Q,X,Y,L;
    char ch;
    
    inline void Get(int *x,int y){
    	for(int i=0;i<26;i++) x[i]=add(H[y+L-1][i],ha-H[y-1][i]*(ll)ci[L]%ha);
    }
    
    inline void solve(){
    	int i;
    	while(Q--){
    		scanf("%d%d%d",&X,&Y,&L);
    		Get(A,X),Get(B,Y);
    		
    		sort(A,A+26),sort(B,B+26);
    		
    		for(i=0;i<26;i++) if(A[i]!=B[i]) break;
    		puts(i==26?"YES":"NO");
    	}
    }
    
    int main(){
    	scanf("%d%d",&n,&Q);
    	
    	ci[0]=1;
    	for(int i=1;i<=n;i++) ci[i]=(ci[i-1]*(ll)b)%ha;
    	
    	for(int i=1;i<=n;i++){
    		ch=getchar();
    		while(ch<'a'||ch>'z') ch=getchar();
    		
    		for(int j=0;j<26;j++) H[i][j]=(H[i-1][j]*(ll)b)%ha;
    		H[i][ch-'a']++;
    	}
    	
    	solve();
    	
    	return 0;
    }
    

      

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  • 原文地址:https://www.cnblogs.com/JYYHH/p/9071465.html
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