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CF A. DZY Loves Hash

时间:2019-05-01 18:39:44      阅读:167      评论:0      收藏:0      [点我收藏+]

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A. DZY Loves Hash
time limit per test
1 second
memory limit per test
256 megabytes
input
standard input
output
standard output

DZY has a hash table with p buckets, numbered from 0 to p?-?1. He wants to insert n numbers, in the order they are given, into the hash table. For the i-th number xi, DZY will put it into the bucket numbered h(xi), where h(x) is the hash function. In this problem we will assume, that h(x)?=?x?mod?p. Operation a?mod?b denotes taking a remainder after division a by b.

However, each bucket can contain no more than one element. If DZY wants to insert an number into a bucket which is already filled, we say a "conflict" happens. Suppose the first conflict happens right after the i-th insertion, you should output i. If no conflict happens, just output -1.

Input

The first line contains two integers, p and n (2?≤?p,?n?≤?300). Then n lines follow. The i-th of them contains an integer xi (0?≤?xi?≤?109).

Output

Output a single integer — the answer to the problem.

Sample test(s)
Input
10 5
0
21
53
41
53
Output
4
Input
5 5
0
1
2
3
4
Output
-1

//题意就是找相等的数,输出第二个的位置,可是要是最先发现的。
比如:10 5
      1 2 2 2 1
输出是3而不是5,由于先找到2和2相等,假设仅仅用for循环,找到的是1和1相等输出是5.
第4个例子卡了非常久,没看懂题目。

。。。

#include <iostream>
using namespace std;
int main()
{   __int64 a[400];
    int n,t,i,j,p,k;
    while(scanf("%d%d",&p,&n)!=EOF)
    {   memset(a,0,sizeof(a));
        t=0;
        for(i=0;i<n;i++)
        {
            scanf("%I64d",&a[i]);
            a[i]=a[i]%p;
        }
        k=n;
        for(i=0;i<n-1;i++)
        {    
            for(j=i+1;j<n;j++)
                if(a[i]==a[j])
                {   
                    k=k<(j+1)?

k:(j+1); t=1; } } if(t==1) printf("%d\n",k); if(t==0) printf("-1\n"); } return 0; }


CF A. DZY Loves Hash

标签:views   tps   lower   for   standard   style   pre   time   ++   

原文地址:https://www.cnblogs.com/ldxsuanfa/p/10800340.html

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