97. Interleaving String

class Solution {
    public boolean isInterleave(String s1, String s2, String s3) {
        if(s1.length()+s2.length()!=s3.length())
            return false;
        boolean [][] dp=new boolean[s1.length()+1][s3.length()+1];
        dp[0][0]=true;
        for(int i=0;i<=s1.length();i++)
            for(int j=i;j<=s3.length();j++)
            {
                if(i>0&&s1.charAt(i-1)==s3.charAt(j-1))
                    dp[i][j]=dp[i-1][j-1];
                int k=j-i;
                if(k<=s2.length()&&k>0&&s2.charAt(k-1)==s3.charAt(j-1))
                    dp[i][j]=dp[i][j]||dp[i][j-1];
            }
        return dp[s1.length()][s3.length()];
    }
}