题解 | 最长公共子串

import java.util.*;


public class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * longest common substring
     * @param str1 string字符串 the string
     * @param str2 string字符串 the string
     * @return string字符串
     */
    public String LCS (String str1, String str2) {
        // write code here
        int m = str1.length();
        int n = str2.length();

        int[][] dp = new int[m+1][n+1];

        for(int i = 1;i<=m;i++){
            for(int j = 1;j<=n;j++){
                if(str1.charAt(i-1)==str2.charAt(j-1)){
                    dp[i][j] = dp[i-1][j-1]+1;
                }else{
                    dp[i][j] = 0;
                }
            }
        }
        int count = 0;
        int leg = 0;
        
        for(int i = 1;i<=m;i++){
            for(int j = 1;j<=n;j++){
                if(dp[i][j]>count){
                    count = dp[i][j];
                    leg = i;
                }
            }
        }

 

        String result = str1.substring(leg-count,leg);


        return result;
    }
}