Leetcode: 14. Longest Common Prefix

Description

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

思路

• 最长的公共前缀，所以，先找出前两个的最长前缀，然后再和后面的比，在比的过程中，记录最小的串的长度，很明显，最长的前缀肯定会小于等于最小串的。算是一个丁点儿优化吧

代码

class Solution {
public:
    string longestCommonPrefix(vector<string>& strs) {
        string res;
        int len = strs.size();
        if(len == 0) return res;
        if(len == 1) return strs[0];

        string prefix;
        int i = 0, j = 0;
        for(; i < strs[0].size() && j < strs[1].size();){
            if(strs[0][i] == strs[1][j]){
                prefix += strs[0][i];
                i++;
                j++;
            }
            else break;
        }
        
        int min_len = 0;
        for(i = 2; i < len; ++i){
            min_len = min(strs[i].size(), prefix.size());
            if(min_len == 0) return "";
            for(j = 0; j < min_len; ++j){
                if(strs[i][j] != prefix[j])
                    break;
            }
            
            prefix = prefix.substr(0, j);
        }
        
        return prefix;
    }
};