leetcode 68: Interleaving String

Interleaving StringAug 31 '12

Given s1, s2, s3, find whether s3 is formed by the interleaving of s1 and s2.

For example,
Given:
s1 = "aabcc",
s2 = "dbbca",

When s3 = "aadbbcbcac", return true.
When s3 = "aadbbbaccc", return false.

 .

 

public class Solution {
    public boolean isInterleave(String s1, String s2, String s3) {
        // Start typing your Java solution below
        // DO NOT write main() function
        int l1 = s1.length();
        int l2 = s2.length();
        int l3 = s3.length();
        
        if(l1+l2!=l3) return false;
        
        boolean[][] hit = new boolean[l1+1][l2+1];
        hit[0][0] = true;
        for(int i=1; i<=l1; i++) {
            if(s1.charAt(i-1) == s3.charAt(i-1) )  
                hit[i][0] = true;
        }
        
        
        for(int i=1; i<=l2; i++) {
            if(s2.charAt(i-1) == s3.charAt(i-1) )  
                hit[0][i] = true;
        }
        
        for(int i=1; i<=l1; i++) {
            for(int j=1; j<=l2; j++) {
                if(s1.charAt(i-1) == s3.charAt(i+j-1)) {
                    hit[i][j] = hit[i-1][j];
                }
                if(s2.charAt(j-1) == s3.charAt(i+j-1) ) {
                    hit[i][j] = hit[i][j-1] | hit[i][j]; 
                }
                
            }
            
        }
        return hit[l1][l2];
    }
}