LeetCode-in-Java

2301. Match Substring After Replacement

Hard

You are given two strings s and sub. You are also given a 2D character array mappings where mappings[i] = [oldi, newi] indicates that you may replace any number of oldi characters of sub with newi. Each character in sub cannot be replaced more than once.

Return true if it is possible to make sub a substring of s by replacing zero or more characters according to mappings. Otherwise, return false.

A substring is a contiguous non-empty sequence of characters within a string.

Example 1:

Input: s = “fool3e7bar”, sub = “leet”, mappings = [[“e”,”3”],[“t”,”7”],[“t”,”8”]]

Output: true

Explanation: Replace the first ‘e’ in sub with ‘3’ and ‘t’ in sub with ‘7’.

Now sub = “l3e7” is a substring of s, so we return true.

Example 2:

Input: s = “fooleetbar”, sub = “f00l”, mappings = [[“o”,”0”]]

Output: false

Explanation: The string “f00l” is not a substring of s and no replacements can be made.

Note that we cannot replace ‘0’ with ‘o’.

Example 3:

Input: s = “Fool33tbaR”, sub = “leetd”, mappings = [[“e”,”3”],[“t”,”7”],[“t”,”8”],[“d”,”b”],[“p”,”b”]]

Output: true

Explanation: Replace the first and second ‘e’ in sub with ‘3’ and ‘d’ in sub with ‘b’.

Now sub = “l33tb” is a substring of s, so we return true.

Constraints:

• 1 <= sub.length <= s.length <= 5000
• 0 <= mappings.length <= 1000
• mappings[i].length == 2
• oldi != newi
• s and sub consist of uppercase and lowercase English letters and digits.
• oldi and newi are either uppercase or lowercase English letters or digits.

Solution

import java.util.HashSet;
import java.util.Set;

@SuppressWarnings("unchecked")
public class Solution {
    private char[] c1;
    private char[] c2;
    private Set<Character>[] al;

    public boolean matchReplacement(String s, String sub, char[][] mappings) {
        c1 = s.toCharArray();
        c2 = sub.toCharArray();
        al = new Set[75];
        for (int i = 0; i < 75; i++) {
            Set<Character> temp = new HashSet<>();
            al[i] = temp;
        }
        for (char[] mapping : mappings) {
            al[mapping[0] - '0'].add(mapping[1]);
        }
        return ans(c1.length, c2.length) == 1;
    }

    private int ans(int m, int n) {
        if (m == 0) {
            return 0;
        }
        if (ans(m - 1, n) == 1) {
            return 1;
        }
        if (m >= n && (c1[m - 1] == c2[n - 1] || al[c2[n - 1] - '0'].contains(c1[m - 1]))) {
            while (n >= 1 && (c1[m - 1] == c2[n - 1] || al[c2[n - 1] - '0'].contains(c1[m - 1]))) {
                n--;
                m--;
            }
            if (n == 0) {
                return 1;
            }
        }
        return 0;
    }
}

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