97. 交错字符串

给定三个字符串 s1, s2, s3, 验证 s3 是否是由 s1 和 s2 交错组成的。

示例 1:

输入: s1 = “aabcc”, s2 = “dbbca”, s3 = “aadbbcbcac”

输出: true

示例 2:

输入: s1 = “aabcc”, s2 = “dbbca”, s3 = “aadbbbaccc”

输出: false

class Solution {

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

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

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

        dp[0][0] = true;

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

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

        }

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

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

        }

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

            for(int j = 1; j < dp[0].length; j++){

                dp[i][j] = (dp[i][j-1] && s1.charAt(j-1) == s3.charAt(i + j-1)) || (dp[i - 1][j] && s2.charAt(i-1) == s3.charAt(i + j-1));

            }

        }

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

    }

}