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답안 #376290

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
376290 2021-03-11T07:37:51 Z tqbfjotld Papričice (COCI20_papricice) C++14
110 / 110
 277 ms 44264 KB 
#include <bits/stdc++.h>
using namespace std;

int sz[200005];
vector<pair<int,int> > paths[200005];
int big[200005];
int big2[200005];
int hd[200005];
vector<int> adjl[200005];
int pa[200005][20];

void dfs(int node, int p){
    pa[node][0] = p;
    for (int x = 1; x<20; x++){
        pa[node][x] = pa[pa[node][x-1]][x-1];
    }
    sz[node] = 1;
    for (auto x : adjl[node]){
        if (x==p) continue;
        dfs(x,node);
        sz[node] += sz[x];
    }
}
void decomp(int node, int p, int head){
    paths[head].push_back({-sz[node],node});
    hd[node] = head;
    int v1 = 0;
    int v2 = 0;
    big2[node] = -1; big[node] = -1;
    for (auto x : adjl[node]){
        if (x==p) continue;
        if (sz[x]>v1){
            v2 = v1;
            big2[node] = big[node];
            v1 = sz[x]; big[node] = x;
        }
        else if (sz[x]>v2){
            v2 = sz[x];
            big2[node] = x;
        }
    }
    if (big[node]!=-1)decomp(big[node],node,head);
    if (big2[node]!=-1)decomp(big2[node],node,big2[node]);
}
int n;

int getv(int a, int b){
    return max(a,max(b,n-a-b))-min(a,min(b,n-a-b));
}

int check(int node){
    //printf("checking %d\n",node);
    if (hd[node]==1){
        int remsize = n-sz[node];
        int thing = remsize/2;
        if (thing==0){
            return 999999999;
        }
        int tt = lower_bound(paths[hd[node]].begin(),paths[hd[node]].end(),make_pair(-thing-sz[node]+1,-1))-paths[hd[node]].begin();
        int splitnode = paths[hd[node]][tt-1].second;
        //printf("split1 = %d\n",splitnode);
        int t2 = -1;
        if (big2[splitnode]!=-1) t2 = lower_bound(paths[big2[splitnode]].begin(),paths[big2[splitnode]].end(),make_pair(1-thing,-1))-paths[big2[splitnode]].begin();
        if (t2==0) {
            int ans = getv(sz[node],sz[splitnode]-sz[node]);
            if (big[splitnode]!=-1 && big[splitnode]!=node)ans = min(ans,getv(sz[node],sz[big[splitnode]]-sz[node]));
            if (big2[splitnode]!=-1) ans = min(ans,getv(sz[node],sz[big2[splitnode]]));
            return ans;
        }
        if (t2==-1){
            int ans = getv(sz[node],sz[splitnode]-sz[node]);
            if (big[splitnode]!=-1 && big[splitnode]!=node)ans = min(ans,getv(sz[node],sz[big[splitnode]]-sz[node]));
            return ans;
        }
        splitnode = paths[big2[splitnode]][t2-1].second;

        //printf("split2 = %d\n",splitnode);
        int ans = getv(sz[node],sz[splitnode]);
        if (big[splitnode]!=-1) ans = min(ans,getv(sz[node],sz[big[splitnode]]));
        return ans;
    }
    else{
        int remsize = n-sz[node];
        int thing = remsize/2;
        if (thing==0){
            return 999999999;
        }
        int imptnode = node;
        for (int x = 19; x>=0; x--){
            if (pa[imptnode][x]!=0 && hd[pa[imptnode][x]]!=1){
                imptnode = pa[imptnode][x];
            }
        }
        int bef = imptnode;
        imptnode = pa[imptnode][0];
        if (sz[big[imptnode]]>=thing){
            //printf("far main branch\n");
            int t2 = lower_bound(paths[1].begin(),paths[1].end(),make_pair(1-thing,-1))-paths[1].begin();
            int splitnode = paths[1][t2-1].second;
            int ans = getv(sz[node],sz[splitnode]);
            if (big[splitnode]!=-1){
                ans = min(ans,getv(sz[node],sz[big[splitnode]]));
            }
            return ans;
        }
        //printf("near main branch\n");
        int tt = lower_bound(paths[1].begin(),paths[1].end(),make_pair(-thing-sz[node]+1,-1))-paths[1].begin();
        int splitnode = paths[1][tt-1].second;
        int ans = getv(sz[node],sz[splitnode]-sz[node]);
        if (big[splitnode]!=-1) ans = min(ans,getv(sz[node],sz[big[splitnode]]));
        if (bef!=node) ans = min(ans,getv(sz[node],sz[bef]-sz[node]));
        return ans;

    }
}

int main(){
    scanf("%d",&n);
    for (int x = 0; x<n-1; x++){
        int a,b;
        scanf("%d%d",&a,&b);
        adjl[a].push_back(b);
        adjl[b].push_back(a);
    }
    dfs(1,0);
    //printf("dfs done\n");
    decomp(1,0,1);
    //printf("decomp done\n");
    int ans = 999999999;
    for (int x = 1; x<=n; x++){
        ans = min(ans,check(x));
    }
    printf("%d",ans);
}

Compilation message

papricice.cpp: In function 'int main()':
papricice.cpp:118:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  118 |     scanf("%d",&n);
      |     ~~~~~^~~~~~~~~
papricice.cpp:121:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  121 |         scanf("%d%d",&a,&b);
      |         ~~~~~^~~~~~~~~~~~~~

Subtask #1
15.0 / 15.0

# 결과 실행 시간 메모리 Grader output
1 Correct 7 ms 9708 KB Output is correct
2 Correct 7 ms 9708 KB Output is correct
3 Correct 7 ms 9708 KB Output is correct
4 Correct 7 ms 9708 KB Output is correct
5 Correct 7 ms 9708 KB Output is correct

Subtask #2
35.0 / 35.0

# 결과 실행 시간 메모리 Grader output
1 Correct 7 ms 9708 KB Output is correct
2 Correct 7 ms 9708 KB Output is correct
3 Correct 7 ms 9708 KB Output is correct
4 Correct 7 ms 9708 KB Output is correct
5 Correct 7 ms 9708 KB Output is correct
6 Correct 8 ms 9964 KB Output is correct
7 Correct 9 ms 10100 KB Output is correct
8 Correct 10 ms 9964 KB Output is correct
9 Correct 8 ms 9964 KB Output is correct
10 Correct 9 ms 10092 KB Output is correct

Subtask #3
60.0 / 60.0

# 결과 실행 시간 메모리 Grader output
1 Correct 7 ms 9708 KB Output is correct
2 Correct 7 ms 9708 KB Output is correct
3 Correct 7 ms 9708 KB Output is correct
4 Correct 7 ms 9708 KB Output is correct
5 Correct 7 ms 9708 KB Output is correct
6 Correct 8 ms 9964 KB Output is correct
7 Correct 9 ms 10100 KB Output is correct
8 Correct 10 ms 9964 KB Output is correct
9 Correct 8 ms 9964 KB Output is correct
10 Correct 9 ms 10092 KB Output is correct
11 Correct 239 ms 37612 KB Output is correct
12 Correct 277 ms 39264 KB Output is correct
13 Correct 197 ms 36716 KB Output is correct
14 Correct 208 ms 37612 KB Output is correct
15 Correct 264 ms 38764 KB Output is correct
16 Correct 162 ms 35048 KB Output is correct
17 Correct 222 ms 37868 KB Output is correct
18 Correct 266 ms 44264 KB Output is correct
19 Correct 246 ms 37676 KB Output is correct
20 Correct 252 ms 39916 KB Output is correct