[LeetCode]Longest Common Prefix

原題連結：http://oj.leetcode.com/problems/longest-common-prefix/

題目描述：

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

題解：

　　依然是一道分治法解的題，類似的還有http://www.cnblogs.com/codershell/p/3592992.html

class Solution {
public:
    string lcp(string str1,string str2){
        int len1 = str1.length();
        int len2 = str2.length();
        int i,j;
        for(i=0,j=0; i<len1&&j<len2; i++,j++){
            if(str1[i] != str2[j] )
                break;
        }
        return str1.substr(0,i);
    }
    string longestCommonPrefix(vector<string> &strs) {
        int size = strs.size();
        if(size == 0)
            return "";
        if(size == 1)
            return strs[0];
        vector<string> A,B;
        for(int i=0; i<size/2; i++){
            A.push_back(strs[i]);
        }
        for(int i=size/2; i<size; i++){
            B.push_back(strs[i]);
        }
        return lcp(longestCommonPrefix(A),longestCommonPrefix(B));
    }
};