Interleaving String

Fair Interleaving StringMy Submissions

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Accepted

Given three strings: s1, s2, s3, determine whether s3 is formed by the interleaving of s1 and s2.

Example

For s1 = "aabcc" s2 = "dbbca"

    - When s3 = "aadbbcbcac", return true.

    - When s3 = "aadbbbaccc", return false.

Challenge Expand 

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public class Solution {
    /**
     * Determine whether s3 is formed by interleaving of s1 and s2.
     * @param s1, s2, s3: As description.
     * @return: true or false.
     */
    public boolean isInterleave(String s1, String s2, String s3) {
        if (s1 == null || s2 == null || s3 == null
            || s3.length() != s1.length() + s2.length()) {
                return false;
        } 
        boolean[][] dp = new boolean[s1.length() + 1][s2.length() + 1];
        dp[0][0] = true;
        for (int i = 1; i < dp.length; i++) {
            if (s3.charAt(i - 1) == s1.charAt(i - 1)) {
                <span style="color:#ff6666;">dp[i][0] = dp[i - 1][0];</span>
            }
        }
        for (int j = 1; j < dp[0].length; j++) {
            if (s3.charAt(j - 1) == s2.charAt(j - 1)) {
                <span style="color:#ff6666;">dp[0][j] = dp[0][j - 1];</span>
            }
        }
        for (int i = 1; i < dp.length; i++) {
            for (int j = 1; j < dp[0].length; j++) {
                char temp = s3.charAt(i + j - 1);
               <span style="color:#ff0000;"> if (temp == s1.charAt(i - 1) && temp == s2.charAt(j - 1)) {
                    dp[i][j] = (dp[i - 1][j] || dp[i][j - 1]);
                } else if (temp == s1.charAt(i - 1)) {
                    dp[i][j] = dp[i - 1][j];
                } else if (temp == s2.charAt(j - 1)) {
                    dp[i][j] = dp[i][j - 1];
                }</span>
            }
        }
        return dp[s1.length()][s2.length()];
    }
}