Interleaving String

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.

这种递归的方法，在集合测试中挂了

class Solution {
public:

    bool interleave(string s1, int len1 , string s2 , int len2 , string s3,int len3)
    {
    	if(len1 + len2 != len3)
			return false;
		if(len3 == s3.length() )
			return true;
		if(len1 == s1.length())
		{
			if(s2[len2] == s3[len3])
				return interleave(s1 , len1 , s2 , len2 + 1 , s3 ,len3 + 1);
			return false;
		}
		if(len2 == s2.length())
		{
			if(s1[len1] == s3[len3])
				return interleave(s1 , len1 + 1 , s2 , len2 , s3 , len3 + 1);
			return false;
		}

		if(s1[len1] == s3[len3] && s2[len2] != s3[len3])
			return interleave(s1,len1 + 1 , s2,len2, s3,len3 + 1);
		else if(s1[len1] != s3[len3] && s2[len2] == s3[len3])
			return interleave(s1 , len1 , s2 , len2 + 1 , s3 , len3 + 1);
		else if(s1[len1] == s3[len3] && s2[len2] == s3[len3])
			return (interleave(s1 , len1 + 1 , s2 ,len2  , s3 , len3 + 1) || interleave(s1 , len1 , s2 , len2 + 1 , s3 , len3 + 1));
		else
			return false;


	}
    bool isInterleave(string s1, string s2, string s3) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function 
		if(s1.length() + s2.length() != s3.length())
			return false;

		return interleave(s1 , 0 , s2 , 0 , s3 , 0);        

    }
};