public boolean isInterleave(String s1, String s2, String s3)

{

if(s1.length() + s2.length() != s3.length()) return false;

if(s1 == null && s2 == null) return false;

if(s3 == null) return false;

if(s1 == null) return s2.equals(s3) ? true : false;

if(s2 == null) return s1.equals(s3) ? true : false;

boolean[][] matrix = new boolean[s1.length()+1][s2.length()+1];

matrix[0][0] = true;

for(int i = 1; i < s1.length()+1; ++i)

{

matrix[i][0] = s1.charAt(i-1) == s3.charAt(i-1) ? true : false;

}

for(int i = 1; i < s2.length()+1; ++i)

{

matrix[0][i] = s2.charAt(i-1) == s3.charAt(i-1) ? true : false;

}

for(int i = 1; i < s1.length()+1; ++i)

{

for(int j = 1; j < s2.length()+1; ++j)

{

if(matrix[i-1][j] == true && s1.charAt(i-1) == s3.charAt(i+j-1))

matrix[i][j] = true;

else if(matrix[i][j-1] == true && s2.charAt(j-1) == s3.charAt(i+j-1))

matrix[i][j] = true;

else

matrix[i][j] = false;

}

}

return matrix[s1.length()][s2.length()];

}