洛谷 P2364 胖男孩

题目传送门

类比最长公共子序列,(f_{i,j,k})表示到(A_i,B_j,C_k)的最大答案,然后跟最长公共自序列一样转移即可

#include<iostream>
#include<cstdio>
#include<cstring>

using namespace std;

string a,b,c,ans[105][105][105];
int f[105][105][105];

inline string dp(string x,string y,string z) {
	memset(f,0,sizeof(f));
	for(int i = 1;i <= x.length(); i++)
		for(int j = 1;j <= y.length(); j++) 
			for(int k = 1;k <= z.length(); k++) {
				if(x[i-1] == y[j-1] && x[i-1] == z[k-1]) {
					f[i][j][k] = f[i-1][j-1][k-1] + 1;
					ans[i][j][k] = ans[i-1][j-1][k-1] + x[i-1];
				}
				else {
					f[i][j][k] = max(f[i-1][j][k],max(f[i][j-1][k],f[i][j][k-1]));
					if(f[i-1][j][k] >= f[i][j-1][k] && f[i-1][j][k] >= f[i][j][k-1])
						ans[i][j][k] = ans[i-1][j][k];
					else 
						if(f[i][j-1][k] >= f[i][j][k-1])
							ans[i][j][k] = ans[i][j-1][k];
						else
							ans[i][j][k] = ans[i][j][k-1];
				}
			}
	return ans[x.length()][y.length()][z.length()];
}

int main() {
	cin >> a >> b >> c;
	a = dp(a,b,c);
	cout << a;
	return 0;
}