Codeforces Round #403 (Div. 1, based on Technocup 2017 Finals) A. Andryusha and Colored Balloons

题目分析

#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;
const int maxn = 2e5+100;

struct Edge{
int to, next;
}e[maxn<<1];

int head[maxn], degree[maxn], color[maxn], tot;

void addedge(int from, int to){
e[tot].to = to;
e[tot].next = head[from];
head[from] = tot++;
}

void dfs(int u, int fa, int ffa){
int tot = 1;
for(int i = head[u]; i != -1; i = e[i].next){
int v = e[i].to;
if(!color[v]){
if(fa == tot){
++tot;
if(ffa == tot) ++tot;
}
if(ffa == tot){
++tot;
if(fa == tot) ++tot;
}
color[v] = tot++;
dfs(v, color[v], color[u]);
}
}
}

void init(){
memset(color, 0, sizeof(color));
memset(degree, 0, sizeof(degree));
memset(head, -1, sizeof(head));
tot = 0;
}

int main(){
#ifdef LOCAL
freopen("input.txt", "r", stdin);
#endif // LOCAL
int n;
while(scanf("%d", &n) != EOF){
int from, to;
init();
for(int i = 1; i < n; i++){
scanf("%d%d", &from, &to);
addedge(from, to);
addedge(to, from);
degree[from]++;
degree[to]++;
}
int ans = 0, temp;
for(int i = 1; i <= n; i++)
if(degree[i]+1 > ans){
temp = i;
ans = max(ans, degree[i]+1);
}
printf("%d\n", ans);
color[temp] = 1;
dfs(temp, 1, -1);
for(int i = 1; i <= n; i++) printf("%d ", color[i]);
printf("\n");
}
return 0;
}