HDU 2614.Beat

#include <iostream>
#include <queue>
#include <algorithm>

#define INF 0x3f3f3f3f

using namespace std;

struct NODE {
short x, y, step;
};

int n, ans;
int map[20][20];
bool vis[20];

void dfs(int cur, int last, int step) {
if (step > ans)ans = step;
for (int i = 0; i < n; i++) {
if (!vis[i] && map[cur][i] >= last) {
vis[i] = true;
dfs(i, map[cur][i], step + 1);
vis[i] = false;
}
}
}

int main() {
while (cin >> n) {
for (int i = 0; i < n; i++)for (int j = 0; j < n; j++)cin >> map[i][j];
ans = 1;
memset(vis, false, sizeof(vis));
vis[0] = true;
dfs(0, 0, 1);
cout << ans << endl;
}

//system("pause");
}