leetcode14. Longest Common Prefix

leetcode14. Longest Common Prefix
思路：
二分法

class Solution {public:    string longestCommonPrefix(vector<string>& strs) {        int maxIndex = strs.size() - 1;         if(maxIndex<0){            return "";        }        return commonPrefix(strs,0,maxIndex);    }    string commonPrefix(vector<string>& strs,int left,int right){        if(left==right){            return strs[left];        }        int middle = left + (right-left)/2;        string leftCommon = commonPrefix(strs,left,middle);        string rightCommon = commonPrefix(strs,middle+1,right);        int cursor = 0;        string tempCommon ="";        while(cursor<leftCommon.size() && cursor<rightCommon.size() && leftCommon[cursor] == rightCommon[cursor]) {tempCommon += leftCommon[cursor];cursor++;}        return tempCommon;    }};