字符串最长公共前缀/后缀

pre

class Solution {
public:
    string longestCommonPrefix(vector<string>& strs) {
        int i,j;
        string r;
        if(strs.size() == 0){
            return r;
        }
        string pre = strs[0];
        for(i=1;i<strs.size();i++){
            pre = get_two_pre(pre,strs[i]);
            if(pre.size() == 0){
                return r;
            }
        }
        return pre;
    }

    string get_two_pre(string &s1,string &s2){
        int len = min(s1.size(),s2.size());
        int index  = 0;
        //string r;
        while(index < len && s1[index] == s2[index]){
            index++;
        }
        return s1.substr(0,index);
    }
};
/*
示例 1:

输入: ["flower","flow","flight"]
输出: "fl"
示例 2:

输入: ["dog","racecar","car"]
输出: ""
解释: 输入不存在公共前缀。

来源：力扣（LeetCode）
链接：https://leetcode-cn.com/problems/longest-common-prefix
著作权归领扣网络所有。商业转载请联系官方授权，非商业转载请注明出处。
*/

post

#include <iostream>
#include <string>
#include <vector>
using namespace std;


string get_two_post(string &s1,string &s2)	;
string longestCommonPostfix(vector<string>& strs) {
	int i,j;
	string r;
	if(strs.size() == 0){
		return r;
	}
	string pre = strs[0];
	for(i=1;i<strs.size();i++){
		pre = get_two_post(pre,strs[i]);
		if(pre.size() == 0){
			return r;
		}
	}
	return pre;
}

string get_two_post(string &s1,string &s2){
	if (s2.size() == 0 || s2[0] == '\0')
	{
		return s1;
	}
	int len = min(s1.size(),s2.size());
	int index  = 0;
	//string r;
	while(index < len && s1[s1.size() - index - 1] == s2[s2.size() - index - 1]){
		index++;
	}
	return s1.substr(s1.size()-index,index);
}
int main(){

	vector<string> strs;

	int n,i;
	string s;
	while (cin>>n)
	{
		if (n == 0)
		{
			break;
		}
		for (i=0;i<n;i++)
		{
			cin>>s;
			strs.push_back(s);
		}
		cout<<longestCommonPostfix(strs)<<endl;
		strs.clear();
	}

	//strs.push_back("aa");
	//strs.push_back("a");
	//strs.push_back("0");
	//string s = longestCommonPostfix(strs);

	//cout<<s;


	return 0;
}
/*
样例输入
3
baba
aba
cba
2
aa
cc
2
aa
a
0
样例输出
ba

a

*/