【洛谷】【搜索+字符串】

题目：[...] (https://www.luogu.org/problemnew/show/P1019)

[Code:]

#include<iostream>
#include<cstdio>
#include<cstring>
using namespace std;

int n, len[21];
int ans, used[21];
string s[21];
char head;

inline int pipei(string a, string b) {
	int lena = a.size(), lenb = b.size();
	int ret = 0, l = min(lena, lenb);
	for(int i=0; i<l; ++i) {
		if(a.substr(lena-i-1, i+1) == b.substr(0, i+1)) return i+1;
	}
	return 0;
}

void dfs(int sum, string now) {
	ans = max(ans, sum);
	for(int i=1; i<=n; ++i) {
		if(used[i] < 2) {
			int k = pipei(now, s[i]);
			if(k == 0 || k == len[i]) continue;
			++used[i];
			int l = now.size();
			string tmp = now;
			for(int j=k; j<len[i]; ++j) {
				now += s[i][j];
			}
			dfs(sum + len[i] - k, now);
			--used[i];
			now = tmp;
		}
	}
}

int main() {
	cin >> n;
	for(int i=1; i<=n; ++i) {
		cin >> s[i];
		len[i] = s[i].size();
	}
	cin >> head;
	for(int i=1; i<=n; ++i) {
		if(s[i][0] == head) {
			used[i] = 1; dfs(len[i], s[i]);
			used[i] = 0;
		}
	}
	printf("%d", ans);
	
	return 0;
}