leetcode 5 Longest Palindromic Substring

代码语言：javascript复制

// Time complexity O(n*n)
class Solution {
public:
    string longestPalindrome(string s) {
        int startIdx = 0, left = 0, right = 0, len = 0;
        for (int i = 0; i < s.size() - 1;   i) {
            if (s[i] == s[i   1]) {
                left = i;
                right = i   1;
                searchPalindrome(s, left, right, startIdx, len);
            }
            left = right = i;
            searchPalindrome(s, left, right, startIdx, len);
        }
        if (len == 0) len = s.size();
        return s.substr(startIdx, len);
    }
    void searchPalindrome(string s, int left, int right, int &startIdx, int &len) {
        int step = 1;
        while ((left - step) >= 0 && (right   step) < s.size()) {
            if (s[left - step] != s[right   step]) break;
              step;
        }
        int wide = right - left   2 * step - 1;
        if (len < wide) {
            len = wide;
            startIdx = left - step   1;
        }
    }
};

substring

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