Codeforces Round #394 (Div. 2) E. Dasha and Puzzle DFS

E. Dasha and Puzzle

链接：

http://codeforces.com/contest/761/problem/E

代码：

#include <iostream>  
#include <vector>  
using namespace std;

typedef pair<int, int> P;
P ans[50];
vector<int> E[100];
int dx[4] = { 0,1,0,-1 };
int dy[4] = { 1,0,-1,0 };
int vis[50];

void dfs(int u, int num, int x, int y, int fromdir) {
    vis[u] = 1;
    ans[u] = P(x, y);
    int dir = 0;
    for (auto i = 0; i < E[u].size(); i++) {
        int v = E[u][i];
        if (vis[v]) continue;
        if (dir == fromdir)    dir++;
        dfs(v, num - 1, x + (1 << num)*dx[dir], y + (1 << num)*dy[dir], (dir + 2) % 4);
        dir++;
    }
}
int main() {
    int n;
    cin >> n;
    for (int i = 1; i < n; i++) {
        int u, v;
        cin >> u >> v;
        E[u].push_back(v);
        E[v].push_back(u);
    }
    for (int i = 0; i < n; i++) {
        if (E[i].size()>4) {
            cout << "NO" << endl;
            return 0;
        }
    }
    dfs(1, 30, 0, 0, -1);
    cout << "YES" << endl;
    for (int i = 1; i <= n; i++) {
        cout << ans[i].first << " " << ans[i].second << endl;
    }
    return 0;
}