Traveling
时间限制: 1 Sec 内存限制: 32 MB
提交: 41 解决: 23
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题目描述
SH likes traveling around the world. When he arrives at a city, he will ask the staff about the number of cities that connected with this city directly. After traveling around a mainland, SH will collate data and judge whether the data is correct.
A group of data is correct when it can constitute an undirected graph.
输入
There are multiple test cases. The first line of each test case is a positive integer N (1<=N<=10000) standing for the number of cities in a mainland. The second line has N positive integers a1, a2, …,an. ai stands for the number of cities that connected directly with the ith city. Input will be ended by the END OF FILE.
输出
If a group of data is correct, output “YES” in one line, otherwise, output “NO”.
样例输入
8
7 7 4 3 3 3 2 1
10
5 4 3 3 2 2 2 1 1 1
样例输出
NO
YES
#include <stdio.h>
#include <iostream>
#include <string.h>
#include <algorithm>
#include <math.h>
#include <ctype.h>
#include <time.h>
#include <queue>
using namespace std;
const int MAXN =10010;
int p[MAXN];
int n;
int solve ()
{
for(int i=0;i<n;i++)
{
for(int j=i+1;j<n;j++)
{
if (p[i]>0 && p[j] >0)
{
p[i]-- ;
p[j]--;
}
}
if (p[i]!=0)
{
return 0;
}
}
return 1;
}
int main()
{
while (scanf("%d",&n)!=EOF)
{
for(int i=0;i<n;i++)
scanf("%d",&p[i]);
if (solve())
printf("YES\n");
else
printf("NO\n");
}
return 0;
}
