Longest Common Prefix (Easy)

Description

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

Analysis

感觉自己的方法不是很好。应该有更快的方法。。求n个字符串的公共前缀

My Solution

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//C++
class Solution {
public:
    string longestCommonPrefix(vector<string> &str) {
        int len = str.size();
        if(len==0)  return "";
        int ans = str[0].length();
        string mod = str[0];
        for(int i = 1;i<len;i++){
            int flag = 1;
            for(int j =0;j<(int)str[i].length()&&j<ans;j++)
            {
                if(mod[j]!=str[i][j]){
                    ans = min(ans,j);
                    flag = 0;
                    break;
                }
            }
            if(flag)
                ans = min(ans,(int)str[i].length());
        }
        return str[0].substr(0,ans);
    }
};