[LeetCode] Longest Common Prefix

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

思路：每个字符串都与第0个字符串比较，设置一个变量，记录每个字符串与第0个字符串不匹配位置的最小值

　　　时间复杂度O(n1+n2+...),空间复杂度O(0)

class Solution {
public:
    string longestCommonPrefix(vector<string> &strs) {
        if (strs.empty()) return "";
        
        int length = strs[0].size() - 1;
        for (int i = 1; i < strs.size(); ++i) {
            for (int j = 0; j <= length; ++j) {
                if (strs[0][j] != strs[i][j])
                    length = j - 1;
            }
        }
        
        return strs[0].substr(0,length + 1);
        
    }
};