未名湖的青蛙

havel定理
函數模組化思想
#include<iostream>
#include <algorithm>
using namespace std;

struct Node
{
int degree;
int index;
};

Node lake[20];
int la[20][20];
int n;

bool compare( Node a, Node b)
{
return a.degree > b.degree;
}

void input()
{
for(int i = 0; i < n; i++)
{
cin >> lake[i].degree;
lake[i].index = i;
}
}

bool judge()
{
memset(la, 0, sizeof(la));
for(int i = 0; i < n-1; i++)
{
sort(lake + i, lake + n, compare);
/*for(int k = 0; k < n; k++)
{
cout << lake[k].index << " ";
}
cout << endl;*/

if(lake[i].degree == 0)
return true;

for(int j = i + 1; j < n; j++)
{
if((lake[i].degree > 0) && (lake[j].degree>0) && (la[lake[i].index][lake[j].index] == 0))
    {
lake[i].degree--;
lake[j].degree--;
la[lake[i].index][lake[j].index] = 1;
la[lake[j].index][lake[i].index] = 1;
     }
}
if(lake[i].degree != 0)
return false;
}
}

void output()
{
for(int i = 0; i < n; i++)
{
for(int j = 0; j < n; j++)
cout << la[i][j] << " ";
cout << endl;
}
}

int main()
{
int t;
cin >> t;

while(t)
{
cin >> n;

   input();

if(judge())
{
cout << "YES" << endl;
output();
}
else
cout << "NO" << endl;
t--;
   if(t != 0)
  cout << endl;
}

    return 0;
}