Longest Common Prefix

最新推荐文章于 2024-02-18 12:25:05 发布

小菜鸟的leetcode

最新推荐文章于 2024-02-18 12:25:05 发布

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文章标签： divide and conquer need another try

本文链接：https://blog.youkuaiyun.com/Scarlett_leetcode/article/details/51303407

版权

Write a function to find the longest common prefix string amongst an array of strings.

Solution

一开始只想到从左到右横扫一遍，却没想到 divide and conquer

class Solution {
public:
    string longestCommonPrefix(vector<string>& strs) {
        if(strs.empty()) return "";
        
        string comp = strs[0];
        for( int i = 1; i < strs.size(); i++ ){
            if(strs[i].size() < comp.size()) comp = strs[i];
        }
        
        int left = 0, right = comp.size() - 1;
        while( left <= right ) {
            int mid = (left + right) / 2;
            bool flag = false;
            for (string str : strs) {
                if(str == comp) continue;
                if(str.substr(0, mid +1) != comp.substr(0, mid + 1)) {
                    right = mid - 1; flag = true; break;
                }
            }
            if(!flag) left = mid + 1;
        }
        return right == -1 ? "" : comp.substr(0, right + 1);
    }
};