第一届省赛 Phone Number

题目描述

We know that if a phone number A is another phone number B’s prefix, B is not able to be called. For an example, A is 123 while B is 12345, after pressing 123, we call A, and not able to call B.
Given N phone numbers, your task is to find whether there exits two numbers A and B that A is B’s prefix.
 

输入

 The input consists of several test cases.
 The first line of input in each test case contains one integer N (0<N<1001), represent the number of phone numbers.
 The next line contains N integers, describing the phone numbers.
 The last case is followed by a line containing one zero.

输出

 For each test case, if there exits a phone number that cannot be called, print “NO”, otherwise print “YES” instead.

示例输入

2
012
012345
2
12
012345
0

示例输出

NO
YES

只要有一个串是另一个串的前缀，就输出NO然后结束。否则输出YES

#include <iostream>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
using namespace std;
int cmp(const void*a,const void*b)
{
    char *A=(char*)a;
    char *B=(char*)b;
    return strlen(A)-strlen(B);
}


int main()
{
    int N;
    while(cin>>N&&N!=0)
    {
        char num[1010][100];
        for(int i=0;i<N;i++)
            cin>>num[i];
        qsort(num,N,sizeof(num[0]),cmp);
        int flag=0;
        for(int i=0;i<N;i++)
        {
            flag=0;
            for(int j=i+1;j<N;j++)
            {
                char *c=strstr(num[j],num[i]);
                if(num[i][0]==num[j][0]&&c==&num[j][0])
                {
                    cout<<"NO"<<endl;
                    flag=1;
                    break;
                }
            }
            if(flag==1)
                break;
        }
        if(flag==0)
            cout<<"YES"<<endl;
    }
    return 0;
}