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답안 #293039

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
293039 2020-09-07T15:44:50 Z 반딧불(#5810) 서류 전달 (ROI16_sending) C++17
53 / 100
 1002 ms 63728 KB 
#include <bits/stdc++.h>
#define LIM 20

using namespace std;

typedef long long ll;
typedef pair<int, int> pi;

struct Path{
    int x, y, idx;
    Path(){}
    Path(int x, int y, int idx): x(x), y(y), idx(idx){}

    bool operator<(const Path &r)const{
        if(x != r.x) return x < r.x;
        if(y != r.x) return y < r.y;
        return idx < r.idx;
    }
};

int n, k;
int par[200002];
vector<int> link[200002];
vector<int> centroidChild[200002];
int subTreeSize[200002];
bool centroidUsed[200002];
int centroidRoot;

int ans, ansX=1, ansY=2;

int getSubTreeSize(int x, int par){
    subTreeSize[x] = 1;
    for(auto &y: link[x]){
        if(y == par || centroidUsed[y]) continue;
        subTreeSize[x] += getSubTreeSize(y, x);
    }
    return subTreeSize[x];
}
int findCentroid(int x){
    int par = 0;
    int treeSize = getSubTreeSize(x, 0);
    while(1){
        int maxTreeSize = 0, maxTreeIdx = -1;
        for(auto &y: link[x]){
            if(centroidUsed[y] || y == par) continue;
            if(subTreeSize[y] > maxTreeSize) maxTreeSize = subTreeSize[y], maxTreeIdx = y;
        }
        if(maxTreeSize <= treeSize / 2){
            break;
        }
        par = x;
        x = maxTreeIdx;
    }
    centroidUsed[x] = 1;
    for(auto &y: link[x]){
        if(centroidUsed[y]) continue;
        int tmp = findCentroid(y);
        centroidChild[x].push_back(tmp);
    }
    return x;
}

int group[200002];
int in[200002], inCnt, depth[200002], inIdx[400002];
vector<pair<int, int> > oppVec[200002];
set<pair<int, int> > sets[200002];
int sparse[400002][LIM];
int cover[400002];

void dfsGroup(int x, int groupNum, int p = 0){
    group[x] = groupNum;
    in[x] = ++inCnt, inIdx[in[x]] = x;
    vector<pair<int, int> >().swap(oppVec[x]);
    sets[x].clear();
    for(auto &y: link[x]){
        if(centroidUsed[y] || y==p) continue;
        depth[y] = depth[x]+1;
        dfsGroup(y, groupNum, x);

        inIdx[++inCnt] = x;
    }
}

inline int LCAdepth(int x, int y){
    x = in[x], y = in[y];
    if(x>y) swap(x, y);
    int d = cover[y-x];
    return min(sparse[x][d], sparse[y-(1<<d)+1][d]);
}

inline void put(int x, pair<int, int> p){
    auto it = sets[x].lower_bound(p);
    if(it != sets[x].end()){
        int tmp = depth[x] + LCAdepth(p.first, it->first);
        if(tmp > ans) ans = tmp, ansX = p.second, ansY = it->second;
    }
    if(it != sets[x].begin()){
        it = prev(it);
        int tmp = depth[x] + LCAdepth(p.first, it->first);
        if(tmp > ans) ans = tmp, ansX = p.second, ansY = it->second;
    }
    sets[x].insert(p);
}

void dfsCalc(int x, int p = 0){
    int maxVal = -1, max_loc = -1;
    for(auto &y: link[x]){
        if(centroidUsed[y] || y==p) continue;
        dfsCalc(y, x);
        if(maxVal < (int)sets[y].size()) maxVal = sets[y].size(), max_loc = y;
    }

    sets[x].swap(sets[max_loc]);
    for(auto &y: link[x]){
        if(centroidUsed[y] || y==p || y==max_loc) continue;
        for(auto p: sets[y]) put(x, p);
        sets[y].clear();
    }
    for(auto p: oppVec[x]){
        put(x, p);
    }
}

void findAnswer(int c, vector<Path> &ust){
    vector<int> nearChild;
    vector<vector<pi> > groupVec;
    vector<vector<Path> > propVec;
    int s;

    for(auto &y: link[c]){
        if(centroidUsed[y]) continue;
        depth[y] = 1; nearChild.push_back(y);
    }
    centroidUsed[c] = 1;
    if(nearChild.empty()) return;
    s = (int)nearChild.size();
    groupVec.resize(s), propVec.resize(s);

    inCnt = depth[c] = 0;
    for(int i=0; i<s; i++){
        dfsGroup(nearChild[i], i);
        inIdx[++inCnt] = c;
    }
    for(int i=inCnt; i>=1; i--){
        sparse[i][0] = depth[inIdx[i]];
        for(int j=1; i+(1<<j)<=inCnt; j++){
            sparse[i][j] = min(sparse[i][j-1], sparse[i+(1<<(j-1))][j-1]);
        }
    }

    for(auto p: ust){
        if(p.x != c && p.y != c && group[p.x] == group[p.y]){
            propVec[group[p.x]].push_back(Path(p.x, p.y, p.idx));
            continue;
        }
        if(p.x != c) groupVec[group[p.x]].push_back({in[p.x], p.idx});
        if(p.y != c) groupVec[group[p.y]].push_back({in[p.y], p.idx});

        if(p.x != c && p.y != c){
            oppVec[p.x].push_back({p.y, p.idx});
            oppVec[p.y].push_back({p.x, p.idx});
        }
    }

    for(int i=0; i<s; i++){ /// check when common subtree is only one
        sort(groupVec[i].begin(), groupVec[i].end());
        for(int j=0; j<(int)groupVec[i].size()-1; j++){
            int tmp = LCAdepth(inIdx[groupVec[i][j].first], inIdx[groupVec[i][j+1].first]);
            if(ans < tmp){
                ans = tmp, ansX = groupVec[i][j].second, ansY = groupVec[i][j+1].second;
            }
        }

        for(int j=0; j<(int)groupVec[i].size(); j++){
            if(j && groupVec[i][j].first == groupVec[i][j-1].first) continue;
            int tmp1 = nearChild[i], tmp2 = inIdx[groupVec[i][j].first];
            if(tmp1 != tmp2) propVec[i].push_back(Path(tmp1, tmp2, groupVec[i][j].second));
        }
    }

    /// check when common subtree is two
    for(int i=0; i<s; i++){
        dfsCalc(nearChild[i]);
    }

    vector<int>().swap(nearChild);
    for(auto &x: groupVec) vector<pi>().swap(x);
    vector<vector<pi> >().swap(groupVec);

    /// propagate to childs
    for(auto &chd: centroidChild[c]){
        findAnswer(chd, propVec[group[chd]]);
        vector<Path>().swap(propVec[group[chd]]);
    }
}

int main(){
    for(int i=1; i<=400000; i++) cover[i] = cover[(i-1)/2]+1;

    scanf("%d %d", &n, &k);

    for(int i=2; i<=n; i++){
        scanf("%d", &par[i]);
        link[i].push_back(par[i]);
        link[par[i]].push_back(i);
    }
    centroidRoot = findCentroid(1);
    memset(centroidUsed, 0, sizeof(centroidUsed));

    vector<Path> st;
    for(int i=1; i<=k; i++){
        int x, y;
        scanf("%d %d", &x, &y);
        st.push_back(Path(x, y, i));
    }

    findAnswer(centroidRoot, st);
    printf("%d\n%d %d", ans, ansX, ansY);
}

Compilation message

sending.cpp: In function 'int main()':
sending.cpp:200:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  200 |     scanf("%d %d", &n, &k);
      |     ~~~~~^~~~~~~~~~~~~~~~~
sending.cpp:203:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  203 |         scanf("%d", &par[i]);
      |         ~~~~~^~~~~~~~~~~~~~~
sending.cpp:213:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  213 |         scanf("%d %d", &x, &y);
      |         ~~~~~^~~~~~~~~~~~~~~~~

Subtask #1
29.0 / 29.0

# 결과 실행 시간 메모리 Grader output
1 Correct 20 ms 25600 KB Output is correct
2 Correct 17 ms 25600 KB Output is correct
3 Correct 19 ms 25600 KB Output is correct
4 Correct 17 ms 25600 KB Output is correct
5 Correct 21 ms 25600 KB Output is correct
6 Correct 18 ms 25576 KB Output is correct
7 Correct 19 ms 25600 KB Output is correct
8 Correct 18 ms 25600 KB Output is correct
9 Correct 19 ms 25600 KB Output is correct
10 Correct 18 ms 25600 KB Output is correct
11 Correct 19 ms 25600 KB Output is correct
12 Correct 18 ms 25600 KB Output is correct
13 Correct 21 ms 25600 KB Output is correct
14 Correct 17 ms 25600 KB Output is correct
15 Correct 17 ms 25600 KB Output is correct
16 Correct 20 ms 25600 KB Output is correct
17 Correct 19 ms 25600 KB Output is correct
18 Correct 20 ms 25600 KB Output is correct
19 Correct 23 ms 25600 KB Output is correct

Subtask #2
12.0 / 12.0

# 결과 실행 시간 메모리 Grader output
1 Correct 20 ms 25600 KB Output is correct
2 Correct 17 ms 25600 KB Output is correct
3 Correct 19 ms 25600 KB Output is correct
4 Correct 17 ms 25600 KB Output is correct
5 Correct 21 ms 25600 KB Output is correct
6 Correct 18 ms 25576 KB Output is correct
7 Correct 19 ms 25600 KB Output is correct
8 Correct 18 ms 25600 KB Output is correct
9 Correct 19 ms 25600 KB Output is correct
10 Correct 18 ms 25600 KB Output is correct
11 Correct 19 ms 25600 KB Output is correct
12 Correct 18 ms 25600 KB Output is correct
13 Correct 21 ms 25600 KB Output is correct
14 Correct 17 ms 25600 KB Output is correct
15 Correct 17 ms 25600 KB Output is correct
16 Correct 20 ms 25600 KB Output is correct
17 Correct 19 ms 25600 KB Output is correct
18 Correct 20 ms 25600 KB Output is correct
19 Correct 23 ms 25600 KB Output is correct
20 Correct 28 ms 26752 KB Output is correct
21 Correct 31 ms 26752 KB Output is correct
22 Correct 34 ms 27000 KB Output is correct
23 Correct 32 ms 27008 KB Output is correct
24 Correct 30 ms 26880 KB Output is correct
25 Correct 24 ms 26880 KB Output is correct
26 Correct 29 ms 27000 KB Output is correct
27 Correct 24 ms 26624 KB Output is correct
28 Correct 29 ms 26656 KB Output is correct
29 Correct 28 ms 26984 KB Output is correct
30 Correct 29 ms 27008 KB Output is correct
31 Correct 29 ms 27008 KB Output is correct
32 Correct 33 ms 27008 KB Output is correct
33 Correct 26 ms 27000 KB Output is correct

Subtask #3
0 / 7.0

# 결과 실행 시간 메모리 Grader output
1 Correct 20 ms 25600 KB Output is correct
2 Correct 17 ms 25600 KB Output is correct
3 Correct 19 ms 25600 KB Output is correct
4 Correct 17 ms 25600 KB Output is correct
5 Correct 21 ms 25600 KB Output is correct
6 Correct 18 ms 25576 KB Output is correct
7 Correct 19 ms 25600 KB Output is correct
8 Correct 18 ms 25600 KB Output is correct
9 Correct 19 ms 25600 KB Output is correct
10 Correct 18 ms 25600 KB Output is correct
11 Correct 19 ms 25600 KB Output is correct
12 Correct 18 ms 25600 KB Output is correct
13 Correct 21 ms 25600 KB Output is correct
14 Correct 17 ms 25600 KB Output is correct
15 Correct 17 ms 25600 KB Output is correct
16 Correct 20 ms 25600 KB Output is correct
17 Correct 19 ms 25600 KB Output is correct
18 Correct 20 ms 25600 KB Output is correct
19 Correct 23 ms 25600 KB Output is correct
20 Correct 28 ms 26752 KB Output is correct
21 Correct 31 ms 26752 KB Output is correct
22 Correct 34 ms 27000 KB Output is correct
23 Correct 32 ms 27008 KB Output is correct
24 Correct 30 ms 26880 KB Output is correct
25 Correct 24 ms 26880 KB Output is correct
26 Correct 29 ms 27000 KB Output is correct
27 Correct 24 ms 26624 KB Output is correct
28 Correct 29 ms 26656 KB Output is correct
29 Correct 28 ms 26984 KB Output is correct
30 Correct 29 ms 27008 KB Output is correct
31 Correct 29 ms 27008 KB Output is correct
32 Correct 33 ms 27008 KB Output is correct
33 Correct 26 ms 27000 KB Output is correct
34 Correct 460 ms 49144 KB Output is correct
35 Incorrect 496 ms 48996 KB Output isn't correct
36 Halted 0 ms 0 KB -

Subtask #4
0 / 8.0

# 결과 실행 시간 메모리 Grader output
1 Correct 20 ms 25600 KB Output is correct
2 Correct 17 ms 25600 KB Output is correct
3 Correct 19 ms 25600 KB Output is correct
4 Correct 17 ms 25600 KB Output is correct
5 Correct 21 ms 25600 KB Output is correct
6 Correct 18 ms 25576 KB Output is correct
7 Correct 19 ms 25600 KB Output is correct
8 Correct 18 ms 25600 KB Output is correct
9 Correct 19 ms 25600 KB Output is correct
10 Correct 18 ms 25600 KB Output is correct
11 Correct 19 ms 25600 KB Output is correct
12 Correct 18 ms 25600 KB Output is correct
13 Correct 21 ms 25600 KB Output is correct
14 Correct 17 ms 25600 KB Output is correct
15 Correct 17 ms 25600 KB Output is correct
16 Correct 20 ms 25600 KB Output is correct
17 Correct 19 ms 25600 KB Output is correct
18 Correct 20 ms 25600 KB Output is correct
19 Correct 23 ms 25600 KB Output is correct
20 Correct 28 ms 26752 KB Output is correct
21 Correct 31 ms 26752 KB Output is correct
22 Correct 34 ms 27000 KB Output is correct
23 Correct 32 ms 27008 KB Output is correct
24 Correct 30 ms 26880 KB Output is correct
25 Correct 24 ms 26880 KB Output is correct
26 Correct 29 ms 27000 KB Output is correct
27 Correct 24 ms 26624 KB Output is correct
28 Correct 29 ms 26656 KB Output is correct
29 Correct 28 ms 26984 KB Output is correct
30 Correct 29 ms 27008 KB Output is correct
31 Correct 29 ms 27008 KB Output is correct
32 Correct 33 ms 27008 KB Output is correct
33 Correct 26 ms 27000 KB Output is correct
34 Correct 460 ms 49144 KB Output is correct
35 Incorrect 496 ms 48996 KB Output isn't correct
36 Halted 0 ms 0 KB -

Subtask #5
0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Correct 450 ms 54284 KB Output is correct
2 Correct 1002 ms 60056 KB Output is correct
3 Incorrect 880 ms 59864 KB Output isn't correct
4 Halted 0 ms 0 KB -

Subtask #6
12.0 / 12.0

# 결과 실행 시간 메모리 Grader output
1 Correct 586 ms 53872 KB Output is correct
2 Correct 698 ms 53356 KB Output is correct
3 Correct 771 ms 63064 KB Output is correct
4 Correct 684 ms 62448 KB Output is correct
5 Correct 658 ms 58532 KB Output is correct
6 Correct 104 ms 54812 KB Output is correct
7 Correct 730 ms 63084 KB Output is correct
8 Correct 163 ms 51828 KB Output is correct
9 Correct 307 ms 50928 KB Output is correct
10 Correct 337 ms 63212 KB Output is correct
11 Correct 533 ms 63720 KB Output is correct
12 Correct 484 ms 63728 KB Output is correct
13 Correct 756 ms 63136 KB Output is correct

Subtask #7
0 / 12.0

# 결과 실행 시간 메모리 Grader output
1 Correct 20 ms 25600 KB Output is correct
2 Correct 17 ms 25600 KB Output is correct
3 Correct 19 ms 25600 KB Output is correct
4 Correct 17 ms 25600 KB Output is correct
5 Correct 21 ms 25600 KB Output is correct
6 Correct 18 ms 25576 KB Output is correct
7 Correct 19 ms 25600 KB Output is correct
8 Correct 18 ms 25600 KB Output is correct
9 Correct 19 ms 25600 KB Output is correct
10 Correct 18 ms 25600 KB Output is correct
11 Correct 19 ms 25600 KB Output is correct
12 Correct 18 ms 25600 KB Output is correct
13 Correct 21 ms 25600 KB Output is correct
14 Correct 17 ms 25600 KB Output is correct
15 Correct 17 ms 25600 KB Output is correct
16 Correct 20 ms 25600 KB Output is correct
17 Correct 19 ms 25600 KB Output is correct
18 Correct 20 ms 25600 KB Output is correct
19 Correct 23 ms 25600 KB Output is correct
20 Correct 28 ms 26752 KB Output is correct
21 Correct 31 ms 26752 KB Output is correct
22 Correct 34 ms 27000 KB Output is correct
23 Correct 32 ms 27008 KB Output is correct
24 Correct 30 ms 26880 KB Output is correct
25 Correct 24 ms 26880 KB Output is correct
26 Correct 29 ms 27000 KB Output is correct
27 Correct 24 ms 26624 KB Output is correct
28 Correct 29 ms 26656 KB Output is correct
29 Correct 28 ms 26984 KB Output is correct
30 Correct 29 ms 27008 KB Output is correct
31 Correct 29 ms 27008 KB Output is correct
32 Correct 33 ms 27008 KB Output is correct
33 Correct 26 ms 27000 KB Output is correct
34 Correct 460 ms 49144 KB Output is correct
35 Incorrect 496 ms 48996 KB Output isn't correct
36 Halted 0 ms 0 KB -

Subtask #8
0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Correct 20 ms 25600 KB Output is correct
2 Correct 17 ms 25600 KB Output is correct
3 Correct 19 ms 25600 KB Output is correct
4 Correct 17 ms 25600 KB Output is correct
5 Correct 21 ms 25600 KB Output is correct
6 Correct 18 ms 25576 KB Output is correct
7 Correct 19 ms 25600 KB Output is correct
8 Correct 18 ms 25600 KB Output is correct
9 Correct 19 ms 25600 KB Output is correct
10 Correct 18 ms 25600 KB Output is correct
11 Correct 19 ms 25600 KB Output is correct
12 Correct 18 ms 25600 KB Output is correct
13 Correct 21 ms 25600 KB Output is correct
14 Correct 17 ms 25600 KB Output is correct
15 Correct 17 ms 25600 KB Output is correct
16 Correct 20 ms 25600 KB Output is correct
17 Correct 19 ms 25600 KB Output is correct
18 Correct 20 ms 25600 KB Output is correct
19 Correct 23 ms 25600 KB Output is correct
20 Correct 28 ms 26752 KB Output is correct
21 Correct 31 ms 26752 KB Output is correct
22 Correct 34 ms 27000 KB Output is correct
23 Correct 32 ms 27008 KB Output is correct
24 Correct 30 ms 26880 KB Output is correct
25 Correct 24 ms 26880 KB Output is correct
26 Correct 29 ms 27000 KB Output is correct
27 Correct 24 ms 26624 KB Output is correct
28 Correct 29 ms 26656 KB Output is correct
29 Correct 28 ms 26984 KB Output is correct
30 Correct 29 ms 27008 KB Output is correct
31 Correct 29 ms 27008 KB Output is correct
32 Correct 33 ms 27008 KB Output is correct
33 Correct 26 ms 27000 KB Output is correct
34 Correct 460 ms 49144 KB Output is correct
35 Incorrect 496 ms 48996 KB Output isn't correct
36 Halted 0 ms 0 KB -