P1019 单词接龙

P1019 单词接龙

#include <bits/stdc++.h>
using namespace std;
int n;
string s[25];
int vis[25];
char ch;
int mc[25][25];//重叠的最小部分
int an;//每次搜到的当前最长长串
int ans = -1;
int match(int x, int y) {
    int p = 1;
    int ky = 0;
    for (int k = s[x].size() - 1; k >= 0; k--){
        
        for (int kx = k; kx < s[x].size(); kx++) {

            if (s[x][kx] != s[y][ky++]) {
                p = 0;
                break;
            }
        }
        if (p)
            return s[x].size() - k;
        ky = 0;
        p = 1;//不行就继续
    }
    return 0;
}
void dfs(int p){
    int f = 0;
    for(int i = 1; i <= n; i++){
        if(vis[i] >= 2 || !mc[p][i])//使用了超过两次 没有重合
            continue;
        if(mc[p][i] == s[p].size() || mc[p][i] == s[i].size())//包含关系
            continue;
        an += s[i].size() - mc[p][i];
        vis[i]++;
        f = 1;
        dfs(i);
        an -= s[i].size() - mc[p][i];
        vis[i]--;
    }
    if(!f) ans = max(ans,an);
    return;
}
int main(){
    //freopen("in","r",stdin);
    ios::sync_with_stdio(0);
    cin >> n;
    for(int i = 1; i <= n; i++) cin >> s[i];
    cin >> ch;
    for(int i = 1; i <= n; i++){
        for(int j = 1; j <= n; j++)
            mc[i][j] = match(i,j);
    }
    for(int i = 1; i <= n; i++){
        if(s[i][0] == ch){
            vis[i]++;
            an = s[i].size();
            dfs(i);
            vis[i] = 0;
        }
    }
    cout << ans;
    return 0;
}