最长公共子序列

题目：牛客网链接

解题思路：（图片来源：https://www.cnblogs.com/hapjin/p/5572483.html）

 

import java.util.Scanner;

public class Main {
	public static int longestCommonSubsquence(String str1, String str2){
        //第一行和第一列要置0
		int m = str1.length()+1;
		int n = str2.length()+1;
		int[][] dp = new int[m][n];
		for(int i = 0; i < m; i++){
			for(int j = 0; j < n ; j++){
                //第一行和第一列要置0
				if(i == 0 || j == 0)
					dp[i][j]=0;
				else if(str1.charAt(i-1)==str2.charAt(j-1)){
					dp[i][j] = dp[i-1][j-1]+1;
				}
				else{
					dp[i][j] = Math.max(dp[i][j-1], dp[i-1][j]);
				}
			}
		}
		return dp[m-1][n-1];
	}

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner in = new Scanner(System.in);
		while(in.hasNext()){
			String str1 = in.next();
			String str2 = in.next();
			System.out.println(longestCommonSubsquence(str1, str2));
		}

	}

}