Problem J: Traveling
Time Limit: 1 Sec Memory Limit: 32 MB
Description
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.
Input
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.
Output
If a group of data is correct, output "YES" in one line, otherwise, output "NO".
Sample Input
8 7 7 4 3 3 3 2 1 10 5 4 3 3 2 2 2 1 1 1
Sample Output
NO YES
上代码
#include<stdio.h>
int a[12345];
int main(){
int n,i,j,flag;
while(~scanf("%d",&n))
{
flag=1;
for(i=0;i<n;i++)
scanf("%d",&a[i]);
for(i=0;i<n;i++)
{
for(j=i+1;j<n;j++)
{
if(a[i]&&a[j]){
a[i]--;
a[j]--;
}
}
if(a[i]!=0)
{
printf("NO\n");
flag=0;
break;
}
}
if(flag) printf("YES\n");
}
return 0;
}
/**************************************************************
Problem: 10
User: Hui
Language: C
Result: Accepted
Time:100 ms
Memory:1012 kb
****************************************************************/