uva 10720 Graph Construction

[code]#include<stdio.h>
#include<string.h>
#include<math.h>
#include<algorithm>
#include<iostream>
using namespace std;

int a[10004],n;
bool cmp(int a,int b)
{
    return a>b;
}

bool fun()
{
    int i,j;
    for(i=0;i<n-1;i++)
    {
        sort(a+i,a+n,cmp);
        if(i+a[i]>=n) return 0;
        for(j=i+1;j<=i+a[i];j++)
        {
            a[j]--;
            if(a[j]<0) return 0;
        }
    }
    if(a[n-1]!=0) return 0;
    return 1;
}

int main()
{

    int i;
    while(~scanf("%d",&n)&&n)
    {
        for(i=0;i<n;i++)
            scanf("%d",&a[i]);
        if(fun()) printf("Possible\n");
        else printf("Not possible\n");

    }
    return 0;
}