oj.uz

답안 #376299

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
376299 2021-03-11T07:59:07 Z dantoh000 Papričice (COCI20_papricice) C++14
0 / 110
 7 ms 9836 KB 
#include <bits/stdc++.h>
using namespace std;
int n;
vector<int> G[200005];
int p[200005];
int col[200005];
int sz[200005];
int root;
void dfs(int u){
    sz[u] = 1;
    for (auto v : G[u]){
        if (v == p[u]) continue;
        p[v] = u;
        dfs(v);
        sz[u] += sz[v];
    }
}
int findcentroid(int u){
    for (auto v : G[u]){
        if (v == p[u]) continue;
        if (sz[v] > n/2) return findcentroid(v);
    }
    return u;
}
vector<int> COL[200005];
set<int> rest;
set<int> hmm;
int curcol = 1;
void dfs2(int u){
    sz[u] = 1;
    COL[col[u]].push_back(u);
    for (auto v : G[u]){
        if (p[u] == v) continue;
        //printf("%d -> %d\n",u,v);
        p[v] = u;
        if (u == root){
            col[v] = curcol++;
        }
        else col[v] = col[u];
        dfs2(v);
        sz[u] += sz[v];
    }
}
int ans;
void process(int a, int b, int c){
    ans = min(ans, max(a,max(b,c)) - min(a,min(b,c)));
}
int main(){
    scanf("%d",&n);
    ans = n;
    for (int i = 0; i < n-1; i++){
        int x,y;
        scanf("%d%d",&x,&y);
        G[x].push_back(y);
        G[y].push_back(x);
    }
    p[1] = -1;
    dfs(1);
    root = findcentroid(1);
    for (int i = 1; i <= n; i++) p[i] = -1;
    col[root] = 0;
    dfs2(root);
    //printf("centroid is %d\n",root);
    for (int c = 1; c <= curcol; c++){
        for (auto u : COL[c]){
            //printf("col %d: %d\n",c,u);
        }
        for (auto u : COL[c]){
            hmm.insert(sz[u]);
        }
        for (auto u : COL[c]){
            int a = sz[u];
            int bad = n-a;
            ///search inside
            auto it = hmm.lower_bound(a+bad/2);
            if (it != hmm.end()){
                int b = *it - a;
                int c = n-a-b;
                process(a,b,c);
            }
            it = hmm.upper_bound(a+bad/2);
            if (it != hmm.end()){
                int b = *it - a;
                int c = n-a-b;
                process(a,b,c);
            }
            /// search outside
            it = rest.lower_bound(bad/2);
            if (it != rest.end()){
                int b = *it;
                int c = n-a-b;
                process(a,b,c);
            }
            it = rest.upper_bound(bad/2);
            if (it != hmm.end()){
                int b = *it;
                int c = n-a-b;
                process(a,b,c);
            }
            //printf("after checking %d, ans = %d\n",u,ans);
        }
        for (auto u : COL[c]){
            rest.insert(sz[u]);
        }
        hmm.clear();
    }

    printf("%d",ans);
}

Compilation message

papricice.cpp: In function 'int main()':
papricice.cpp:65:19: warning: unused variable 'u' [-Wunused-variable]
   65 |         for (auto u : COL[c]){
      |                   ^
papricice.cpp:49:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   49 |     scanf("%d",&n);
      |     ~~~~~^~~~~~~~~
papricice.cpp:53:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   53 |         scanf("%d%d",&x,&y);
      |         ~~~~~^~~~~~~~~~~~~~

Subtask #1
0 / 15.0

# 결과 실행 시간 메모리 Grader output
1 Correct 7 ms 9836 KB Output is correct
2 Correct 7 ms 9708 KB Output is correct
3 Incorrect 7 ms 9708 KB Output isn't correct
4 Halted 0 ms 0 KB -

Subtask #2
0 / 35.0

# 결과 실행 시간 메모리 Grader output
1 Correct 7 ms 9836 KB Output is correct
2 Correct 7 ms 9708 KB Output is correct
3 Incorrect 7 ms 9708 KB Output isn't correct
4 Halted 0 ms 0 KB -

Subtask #3
0 / 60.0

# 결과 실행 시간 메모리 Grader output
1 Correct 7 ms 9836 KB Output is correct
2 Correct 7 ms 9708 KB Output is correct
3 Incorrect 7 ms 9708 KB Output isn't correct
4 Halted 0 ms 0 KB -