【codeforces】Bear and Three Balls（排序，去重）

Bear and Three Balls

Time Limit:2000MS     Memory Limit:262144KB     64bit
IO Format:%I64d & %I64u

Submit Status

Description

Limak is a little polar bear. He has n balls, the i-th
ball has size ti.

Limak wants to give one ball to each of his three friends. Giving gifts isn't easy — there are two rules Limak must obey to make friends happy:

• No two friends can get balls of the same size.
• No two friends can get balls of sizes that differ by more than 2.

For example, Limak can choose balls with sizes 4, 5 and 3,
or balls with sizes 90, 91 and 92.
But he can't choose balls with sizes5, 5 and 6 (two
friends would get balls of the same size), and he can't choose balls with sizes 30, 31 and 33 (because
sizes 30and 33 differ by more than 2).

Your task is to check whether Limak can choose three balls that satisfy conditions above.

Input

The first line of the input contains one integer n (3 ≤ n ≤ 50) —
the number of balls Limak has.

The second line contains n integers t1, t2, ..., tn (1 ≤ ti ≤ 1000)
where ti denotes the size of the i-th
ball.

Output

Print "YES" (without quotes) if Limak can choose three balls of distinct sizes, such that any two of them differ by no more
than 2. Otherwise, print "NO" (without quotes).

Sample Input

Input

4
18 55 16 17

Output

YES

Input

6
40 41 43 44 44 44

Output

NO

Input

8
5 972 3 4 1 4 970 971

Output

YES

题意：查找一个数组里面是否有三个连续的数。

#include<stdio.h>
#include<string.h>
#include<algorithm>
using namespace std;
int main()
{
	int n,a[100],i;
	int b[100];
	while(~scanf("%d",&n))
	{
		int flag=0;
		int j=0;
		for(i=0;i<n;i++) scanf("%d",&a[i]);
		sort(a,a+n);
		for(i=0;i<n;i++)
		{
			if(a[i]!=a[i+1]) b[j++]=a[i];
		}
		for(i=0;i<j;i++)
		{
			if(b[i]==b[i+1]-1&&b[i]==b[i+2]-2)
			{
				flag+=1;
				break;
			}
		}
		if(flag!=0) printf("YES\n");
		else printf("NO\n");
	}
	return 0;
 } 

或者使用unique函数进行去重

#include<stdio.h>
#include<algorithm>
#include<iostream>
using namespace std;
int main()
{
	int n,a[100],i;
	while(~scanf("%d",&n))
	{
		int flag=0;
		for(i=0;i<n;i++) scanf("%d",&a[i]);
		sort(a,a+n);
		n=unique(a,a+n)-a;
		for(i=0;i<n;i++)
		{
			if(a[i]==a[i+1]-1&&a[i+1]==a[i+2]-1) flag+=1;
		}
		if(flag) printf("YES\n");
		else printf("NO\n");
	}
	return 0;
}

关于去重函数的更多用法在http://blog.csdn.net/tomorrowtodie/article/details/51907471里面