LCS + 输出最长公共子序列

带输出：

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
char a[1005], b[1005];
int dp[1005][1005];

void lcs(char a[], char b[]){
	int len1 = strlen(a);
	int len2 = strlen(b);
	memset(dp, 0, sizeof(dp));
	for(int i=1; i<=len1; i++)
		for(int j=1; j<=len2; j++){
			if(a[i-1]==b[j-1]) dp[i][j] = dp[i-1][j-1] + 1;
			else dp[i][j] = max(dp[i-1][j], dp[i][j-1]);
		}
	printf("%d\n", dp[len1][len2]);
}

void print(char a[], char b[]){
	stack <char> s;
	int len1 = strlen(a);
	int len2 = strlen(b);
	while(dp[len1][len2]){
		if(dp[len1][len2] == dp[len1-1][len2]) len1--;
		else if(dp[len1][len2] == dp[len1][len2-1]) len2--;
		else {
			len1--, len2--;
			s.push(a[len1]);
		}
	}
	while(!s.empty()){
		printf("%c", s.top());
		s.pop();
	}
	puts("");
}

int main(){
	while(~scanf("%s %s", a, b)){
		lcs(a, b);
		print(a, b);
	}
}