最长公共子序列 代码框架见下 

#include<iostream>
using namespace std;

#define maxn 1010
#define maxm 1010
#define type int

int getLCS(int n, type a[], int m, type b[], int dp[maxn][maxm], char path[maxn][maxm]) {
	;
	//dp[i][j]代表a[1:i], b[1:j] 这两个数组的最长公共子序列的长度
	//reture dp[n][m]
	for (int i = 1; i <= n; ++i) {
		for (int j = 1; j <= m; ++j) {
			if (a[i] == b[j]) {
				dp[i][j] = dp[i - 1][j - 1] + 1;
				path[i][j] = 0;
			}
			else if (dp[i - 1][j] > dp[i][j - 1]) {
				dp[i][j] = dp[i - 1][j];
				path[i][j] = 1;
			}
			else {
				dp[i][j] = dp[i][j - 1];
				path[i][j] = 2;
			}
		}
	}
	return dp[n][m];
}

int dp[maxn][maxm];
char path[maxn][maxm];
int a[maxn], b[maxm];

int main() {
	int n, m;
	cin >> n >> m;
	for (int i = 1; i <= n; ++i) {
		cin >> a[i];
	}
	for (int i = 1; i <= m; ++i) {
		cin >> b[i];
	}
	cout << getLCS(n, a, m, b, dp, path) << endl;
	return 0;
}