제출 #532850

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
532850		79brue	Newspapers (CEOI21_newspapers)	C++14	0 / 100	1 ms	324 KiB

newspapers

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

int n, m;
vector<int> link[1002];
int maxDepth, maxIdx;
int p[1002];

int dfs(int x, int par = -1, int depth = 0){
    vector<int> vec (1, 0);
    p[x] = par;
    if(maxDepth < depth) maxIdx = x, maxDepth = depth;
    for(auto y: link[x]){
        if(y==par) continue;
        int tmp = dfs(y, x, depth+1);
        vec.push_back(tmp+1);
    }

    sort(vec.rbegin(), vec.rend());
    if(par == -1){
        if(vec.size() >= 3 && vec[2] >= 3){
            puts("NO");
            exit(0);
        }
    }
    return vec[0];
}

int depth[1002];
vector<int> line;
vector<vector<int> > lineChild;
vector<vector<int> > lineChildCnt;
vector<int> ans;

int main(){
    scanf("%d %d", &n, &m);
    if(m!=n-1){
        puts("NO");
        return 0;
    }

    for(int i=1; i<n; i++){
        int x, y;
        scanf("%d %d", &x, &y);
        link[x].push_back(y), link[y].push_back(x);
    }

    for(int i=1; i<=n; i++){
        dfs(i);
    }

    maxDepth = 0; dfs(1);
    int A = maxIdx;
    maxDepth = 0; dfs(A);
    int B = maxIdx;

    {
        int x = B;
        while(x != -1){
            line.push_back(x);
            depth[x] = 1;
            x = p[x];
        }
        reverse(line.begin(), line.end());
    }
    lineChild.resize(line.size());
    lineChildCnt.resize(line.size());

    for(int i=1; i<=n; i++){
        if(depth[i] == 1) continue;
        if(depth[p[i]] == 1){
            depth[i] = 2;
            int idx = find(line.begin(), line.end(), p[i]) - line.begin();
            lineChild[idx].push_back(i);
            lineChildCnt[idx].push_back(0);
        }
    }
    for(int i=1; i<=n; i++){
        if(depth[i] == 1 || depth[i] == 2) continue;
        if(depth[p[i]] == 2){
            depth[i] = 3;
            int idx = find(line.begin(), line.end(), p[p[i]]) - line.begin();
            lineChildCnt[idx][find(lineChild[idx].begin(), lineChild[idx].end(), p[i]) - lineChild[idx].begin()]++;
        }
    }

    for(int i=1; i<(int)line.size()-1; i++){
        ans.push_back(line[i]);
        for(int j=0; j<(int)lineChild[i].size(); j++){
            if(lineChildCnt[i][j]) ans.push_back(lineChild[i][j]), ans.push_back(line[i]);
        }
    }
    if(count(ans.begin(), ans.end(), ans.back()) >= 2) ans.pop_back();
    if(count(ans.begin(), ans.end(), ans[0]) >= 2) ans.erase(ans.begin());

    printf("YES\n%d\n", (int)ans.size()*2);
    for(auto x: ans) printf("%d ", x);
    if((int)ans.size() % 2 == 0){
        reverse(ans.begin(), ans.end());
    }
    for(auto x: ans) printf("%d ", x);
}

컴파일 시 표준 에러 (stderr) 메시지

newspapers.cpp: In function 'int main()':
newspapers.cpp:39:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   39 |     scanf("%d %d", &n, &m);
      |     ~~~~~^~~~~~~~~~~~~~~~~
newspapers.cpp:47:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   47 |         scanf("%d %d", &x, &y);
      |         ~~~~~^~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 12
• Subtask 2: 0 / 8
• Subtask 3: 0 / 80