[LeetCode] Longest Common Prefix

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

先把排好序的前两个字符串的最大前缀求出来，然后看这个前缀是否是其他字符串的前缀，如果不是，缩短这个前缀再看是否是其他字符串的前缀

class Solution {
public:
    string longestCommonPrefix(vector<string> &strs) {
        string result;
        int len = strs.size();
        if(len==0)
            return "";
        else if(len==1)
            return strs[0];
        sort(strs.begin(),strs.end());
        string str1 = strs[0];
        string str2 = strs[1];
        int len1 = str1.size()>str2.size()?str2.size():str1.size();
        int i;
        for( i=0;i<len1;i++){
            if(str1[i]!=str2[i]){
                result = str1.substr(0,i);
                break;
            }
        
        }//end for
        if(i==len1)
           result = str1.substr(0,len1);

        int length = result.size();
        while(length>=0){
            string theS = result.substr(0,length);
            int i;
            for(i=2;i<len;i++){
                if(strs[i].substr(0,length)!= theS)
                    break;
            }
            if(i==len)
                return theS;
            length--;
        }
        return result;
    }//end func
};