Interleaving String

lc 97 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 双序列动态规划

1. state
2. function
3. initialize fi[i][0] f[0][i] 4.answer

class Solution {
    public boolean isInterleave(String s1, String s2, String s3) {
        if (s1.length() + s2.length() != s3.length()) return false;
        boolean[][] f = new boolean[s1.length() + 1][s2.length() + 1];
        f[0][0] = true;

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

        for (int j = 1; j <= s2.length(); j++) {
            if(s3.charAt(j - 1) == s2.charAt(j - 1) && f[0][j - 1])
                f[0][j] = true;
        }        

        for (int i = 1; i <= s1.length(); i++) {
            for (int j = 1; j <= s2.length(); j++) {
                if(f[i - 1][j - 1]) {
                    if((s1.charAt(i - 1) == s3.charAt(i + j - 2) && s2.charAt(j - 1) == s3.charAt(i + j - 1))
                       ||(s1.charAt(i - 1) == s3.charAt(i + j - 1) && s2.charAt(j - 1) == s3.charAt(i + j -2))){
                        f[i][j] = true;
                        continue;
                    }    
                } 
                if(f[i][j - 1]) {
                    if(s2.charAt(j - 1) == s3.charAt(i + j - 1)){
                        f[i][j] = true;
                        continue;
                    }      
                } 
                if(f[i - 1][j]) {
                    if(s1.charAt(i - 1) == s3.charAt(i + j - 1)){
                        f[i][j] = true;
                        continue;
                    }      
                }   
            }
        }
        return f[s1.length()][s2.length()];   
    }
}