POJ1659 Frogs' Neighborhood

第一道ACM题，做了三天做出来了好高兴啊！在Veegin那里学会了怎样使用数组，然后又自己摸索看书学会递归。师兄教我用C++，嗯，比较好用。然后，感觉递归很灵活很灵活，可能是第一次写，不熟悉。不管如何，还是写出来了，哈哈哈！继续再接再厉！48行代码，鸡冻死我了！

#include <iostream>
#define MAXN 250
#define MaxInt 0x3f3f3f3f
using namespace std;

int T, N, flow[MAXN][MAXN], cap[MAXN][MAXN], a[MAXN];

bool search(int row, int col, int remain) {
if (remain < 0) return false;
if (col == N) {
if (remain > 1) return false;
cap[row][col] = remain;
if (row == N) return cap[row][col] == 0;
return search(row + 1, 1, a[row + 1]);
}
if (row > col) {
cap[row][col] = cap[col][row];
return search(row, col + 1, remain - cap[row][col]);
}
cap[row][col] = 0;
if (search(row, col + 1, remain)) return true;
if (row == col) return false;
cap[row][col] = 1;
return search(row, col + 1, remain - 1);
}

int main()
{
int i, j;
cin >> T;
while (T--)
{
cin >> N;
for (i = 1; i <= N; ++i) cin >> a[i];
if (search(1, 1, a[1])) {
cout << "YES\n";
for (i = 1; i <= N; i++) {
for (j = 1; j <= N; j++) {
cout << cap[i][j] << " ";
}
cout << '\n';
}
}
else cout << "NO\n";
if (T >= 1) cout << endl;
}
return 0;
}