Traveling 【图的性质】

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;}