97. 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.

class Solution {
public boolean isInterleave(String s1, String s2, String s3) {
if ((s1.length() + s2.length()) != s3.length())
return false;

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

matrix[0][0] = true;

for (int i = 1; i < matrix[0].length; i++){
matrix[0][i] = matrix[0][i-1] && (s1.charAt(i-1) == s3.charAt(i-1));
}

for (int i = 1; i < matrix.length; i++){
matrix[i][0] = matrix[i-1][0] && (s2.charAt(i-1) == s3.charAt(i-1));
}

for (int i = 1; i < matrix.length; i++){
for (int j = 1; j < matrix[0].length; j++){
matrix[i][j] = (matrix[i-1][j] && (s2.charAt(i-1) == s3.charAt(i+j-1)))
|| (matrix[i][j-1] && (s1.charAt(j-1) == s3.charAt(i+j-1)));
}
}

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