LeetCode-in-All

131. Palindrome Partitioning

Medium

Given a string s, partition s such that every substring of the partition is a palindrome. Return all possible palindrome partitioning of s.

A palindrome string is a string that reads the same backward as forward.

Example 1:

Input: s = “aab”

Output: [[“a”,”a”,”b”],[“aa”,”b”]]

Example 2:

Input: s = “a”

Output: [[“a”]]

Constraints:

• 1 <= s.length <= 16
• s contains only lowercase English letters.

Solution

#include <vector>
#include <string>

class Solution {
public:
    std::vector<std::vector<std::string>> partition(std::string s) {
        std::vector<std::vector<std::string>> res;
        std::vector<std::string> currArr;
        backtracking(res, currArr, s, 0);
        return res;
    }

private:
    void backtracking(std::vector<std::vector<std::string>>& res, std::vector<std::string>& currArr, const std::string& s, int start) {
        if (start == s.length()) {
            res.push_back(currArr);
        }
        for (int end = start; end < s.length(); end++) {
            if (!isPalindrome(s, start, end)) {
                continue;
            }
            currArr.push_back(s.substr(start, end - start + 1));
            backtracking(res, currArr, s, end + 1);
            currArr.pop_back();
        }
    }

    bool isPalindrome(const std::string& s, int start, int end) {
        while (start < end && s[start] == s[end]) {
            start++;
            end--;
        }
        return start >= end;
    }
};

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