Interleaving String

    //two dimensions dp    public boolean isInterleave(String s1, String s2, String s3) {        // Start typing your Java solution below        // DO NOT write main() function        if(s1.length() + s2.length() != s3.length()) return false;        if(s1.length() == 0 && s2.length() == 0 && s3.length() == 0) return true;        boolean[][] dp = new boolean[s1.length() + 1][s2.length() + 1];        dp[0][0] = true;        for(int i = 1; i <= s1.length(); i++) {            if(s1.charAt(i - 1) == s3.charAt(i - 1) && dp[i - 1][0] == true) dp[i][0] = true;            else dp[i][0] = false;        }        for(int i = 1; i <= s2.length(); i++) {            if(s2.charAt(i - 1) == s3.charAt(i - 1) && dp[0][i - 1] == true) dp[0][i] = true;            else dp[0][i] = false;        }        for(int i = 1; i <= s1.length(); i++) {            for(int j = 1; j <= s2.length(); j++) {                if(dp[i - 1][j] == true) {                    if(s1.charAt(i - 1) == s3.charAt(i + j - 1)) dp[i][j] = true;                    else dp[i][j] = false;                }else if(dp[i][j - 1] == true) {                    if(s2.charAt(j - 1) == s3.charAt(i + j - 1)) dp[i][j] = true;                    else dp[i][j] = false;                }            }        }        return dp[s1.length()][s2.length()];    }