Codeforces Round #403 (Div. 2, based on Technocup 2017 Finals

C题思路：生成树上的dfs，完全没见过，留作复习

代码：

#include<stdio.h>#include<iostream>#include<string.h>#include<algorithm>#include<queue>#include<string>#include<vector>#define maxn 210000using namespace std;int n;vector<int>aaa[maxn];int power[maxn];int color[maxn];void dfs(int x, int fa) {//对第x个节点的子节点们开始染色，x的父节点是fAint c = 1;for (int i = 0; i < aaa[x].size(); i++) {int temp = aaa[x][i];if (color[temp] != 0)continue;while (c == color[x] || c == color[fa])c++;color[temp] = c;dfs(temp, x);c++;}}int ans;int main() {memset(color, 0, sizeof(color));memset(power, 0, sizeof(power));ans = 0;scanf("%d", &n);int a, b;for (int i = 1; i < n; i++) {scanf("%d %d", &a, &b);power[a]++; power[b]++;ans = max(ans, max(power[a], power[b]));aaa[a].push_back(b);aaa[b].push_back(a);}ans++;cout << ans << endl;dfs(1, 0);for (int i = 1; i <= n; i++) {if (i != 1)printf(" ");printf("%d", color[i]);}printf("\n");}