[LeetCode] 97. Interleaving String

Problem

Given s1, s2, s3, find whether s3 is formed by the interleaving of s1 and s2.

Example 1:

Input: s1 = "aabcc", s2 = "dbbca", s3 = "aadbbcbcac"
Output: true
Example 2:

Input: s1 = "aabcc", s2 = "dbbca", s3 = "aadbbbaccc"
Output: false

Solution

class Solution {
    public boolean isInterleave(String s1, String s2, String s3) {
        int l1 = s1.length(), l2 = s2.length(), l3 = s3.length();
        if (l1+l2 != l3) return false;
        boolean[][] dp = new boolean[l1+1][l2+1];
        dp[0][0] = true;
        for (int i = 1; i <= l1; i++) dp[i][0] = dp[i-1][0] && s1.charAt(i-1) == s3.charAt(i-1);
        for (int j = 1; j <= l2; j++) dp[0][j] = dp[0][j-1] && s2.charAt(j-1) == s3.charAt(j-1);
        for (int i = 1; i <= l1; i++) {
            for (int j = 1; j <= l2; j++) {
                dp[i][j] = dp[i-1][j] && s1.charAt(i-1) == s3.charAt(i+j-1) ||
                    dp[i][j-1] && s2.charAt(j-1) == s3.charAt(i+j-1);
            }
        }
        return dp[l1][l2];
    }
}