79 · 最长公共子串 Longest Common Substring

79 · 最长公共子串 Longest Common Substring

描述
Given two strings, find the longest common substring.

Return the length of it.
Input:

stringA = “ABCD”
stringB = “CBCE”
Output:

2
Explanation:

Longest common substring is “BC”

public class Solution {
    /**
     * @param A: A string
     * @param B: A string
     * @return: the length of the longest common substring.
     */
    public int longestCommonSubstring(String A, String B) {
        // write your code hepublic class Solution {
        if(A == null || B == null || A.length() == 0  || B.length() == 0 ){
            return 0 ;
        }
        int n = A.length() , m = B.length() ;
        int[][] f = new int[n+1][m+1] ;
        for(int i = 0 ; i <= m ; i++){
            f[0][i] = 0 ;
        }
        for(int j = 0 ; j <= n ; j++){
            f[j][0] = 0 ;
        }
        
        for(int i = 1 ; i <= n ; i++){
            for(int j = 1 ; j <= m ; j++){
               f[i][j] = 0 ;
               if(A.charAt(i-1)  == B.charAt(j-1)){
                   f[i][j] = f[i-1][j-1] + 1 ;
               }
               
                
            }
        }
        int max = 0 ;
        for(int i = 0 ; i <= n ; i++){
            for(int j = 0 ; j <= m ; j++){
               max = Math.max(f[i][j] , max) ;
            }
        }
        return max ;


    }
}