UVALive 6507 Passwords

Passwords

Time Limit: 3000ms

Memory Limit: 131072KB

This problem will be judged on UVALive. Original ID: 6507
64-bit integer IO format: %lld      Java class name: Main

 

解题：好高深的hash啊

 #include <bits/stdc++.h>
 using namespace std;
 typedef long long LL;
 const int maxn = ;
 const int base = ;
 const int mod = 1e9+;
 char str[maxn][];
 LL hs[maxn][],B[];
 int n;
 unordered_map<LL,int>ump;
 void init(){
     B[] = ;
     for(int i = ; i < ; ++i)
         B[i] = B[i-]*base%mod;
 }
 LL calc(int i,int L,int R){
     return ((hs[i][R] - hs[i][L-]*B[R - L + ])%mod + mod)%mod;
 }
 void solve(){
     ump.clear();
     for(int i = ; i < n; ++i){
         for(int j = ,len = strlen(str[i] + ); j <= len; ++j){
             hs[i][j] = (hs[i][j-]*base + str[i][j])%mod;
             ump[hs[i][j]]++;
         }
     }
     int a = ,b = ;
     for(int i = ; i < n; ++i){
         int len = strlen(str[i] + );
         for(int j = ; j <= len; ++j) --ump[hs[i][j]];
         for(int j = ; j <= len; ++j){
             LL suffix = calc(i,len - j + ,len);
             if(!ump[suffix]) continue;
             int x = ,y = ;
             LL prefix = suffix;
             for(int k = ; k*j <= len; ++k){
                 LL suffix2 = calc(i,len - j*k + ,len);
                 prefix = (prefix*B[j] + suffix)%mod;
                 if(suffix2 != prefix) break;
                 if(ump[prefix]) x = k;
                 y = k;
             }
             if(x == y && x == ) continue;
             if(x == y) --x;
             if(j*(x + y) > a + b){
                 a = x*j;
                 b = y*j;
             }
         }
         for(int j = ; j <= len; ++j) ump[hs[i][j]]++;
     }
     printf("%d %d\n",a,b);
 }
 int main(){
     int kase;
     init();
     scanf("%d",&kase);
     while(kase--){
         scanf("%d",&n);
         for(int i = ; i < n; ++i)
             scanf("%s",str[i] + );
         solve();
     }
     return ;
 }
 /*
 2
 3
 abcabe
 defg
 bcabab
 */