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답안 #293033

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
293033 2020-09-07T15:41:43 Z 반딧불(#5810) 서류 전달 (ROI16_sending) C++17
53 / 100
 913 ms 63852 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);
    }
    if(nearChild.empty()) return;
    centroidUsed[c] = 1;
    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]){
        assert(0 <= group[chd] && group[chd] < s);
        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:201:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  201 |     scanf("%d %d", &n, &k);
      |     ~~~~~^~~~~~~~~~~~~~~~~
sending.cpp:204:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  204 |         scanf("%d", &par[i]);
      |         ~~~~~^~~~~~~~~~~~~~~
sending.cpp:214:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  214 |         scanf("%d %d", &x, &y);
      |         ~~~~~^~~~~~~~~~~~~~~~~

Subtask #1
29.0 / 29.0

# 결과 실행 시간 메모리 Grader output
1 Correct 19 ms 25600 KB Output is correct
2 Correct 19 ms 25600 KB Output is correct
3 Correct 18 ms 25600 KB Output is correct
4 Correct 19 ms 25600 KB Output is correct
5 Correct 18 ms 25600 KB Output is correct
6 Correct 19 ms 25688 KB Output is correct
7 Correct 18 ms 25600 KB Output is correct
8 Correct 18 ms 25600 KB Output is correct
9 Correct 20 ms 25600 KB Output is correct
10 Correct 21 ms 25592 KB Output is correct
11 Correct 18 ms 25600 KB Output is correct
12 Correct 19 ms 25632 KB Output is correct
13 Correct 19 ms 25728 KB Output is correct
14 Correct 19 ms 25600 KB Output is correct
15 Correct 18 ms 25600 KB Output is correct
16 Correct 19 ms 25600 KB Output is correct
17 Correct 20 ms 25600 KB Output is correct
18 Correct 18 ms 25600 KB Output is correct
19 Correct 20 ms 25600 KB Output is correct

Subtask #2
12.0 / 12.0

# 결과 실행 시간 메모리 Grader output
1 Correct 19 ms 25600 KB Output is correct
2 Correct 19 ms 25600 KB Output is correct
3 Correct 18 ms 25600 KB Output is correct
4 Correct 19 ms 25600 KB Output is correct
5 Correct 18 ms 25600 KB Output is correct
6 Correct 19 ms 25688 KB Output is correct
7 Correct 18 ms 25600 KB Output is correct
8 Correct 18 ms 25600 KB Output is correct
9 Correct 20 ms 25600 KB Output is correct
10 Correct 21 ms 25592 KB Output is correct
11 Correct 18 ms 25600 KB Output is correct
12 Correct 19 ms 25632 KB Output is correct
13 Correct 19 ms 25728 KB Output is correct
14 Correct 19 ms 25600 KB Output is correct
15 Correct 18 ms 25600 KB Output is correct
16 Correct 19 ms 25600 KB Output is correct
17 Correct 20 ms 25600 KB Output is correct
18 Correct 18 ms 25600 KB Output is correct
19 Correct 20 ms 25600 KB Output is correct
20 Correct 32 ms 26752 KB Output is correct
21 Correct 31 ms 26752 KB Output is correct
22 Correct 31 ms 27000 KB Output is correct
23 Correct 30 ms 27008 KB Output is correct
24 Correct 35 ms 26872 KB Output is correct
25 Correct 20 ms 26880 KB Output is correct
26 Correct 36 ms 27004 KB Output is correct
27 Correct 25 ms 26624 KB Output is correct
28 Correct 27 ms 26752 KB Output is correct
29 Correct 29 ms 26880 KB Output is correct
30 Correct 31 ms 27008 KB Output is correct
31 Correct 28 ms 27008 KB Output is correct
32 Correct 30 ms 27008 KB Output is correct
33 Correct 31 ms 27008 KB Output is correct

Subtask #3
0 / 7.0

# 결과 실행 시간 메모리 Grader output
1 Correct 19 ms 25600 KB Output is correct
2 Correct 19 ms 25600 KB Output is correct
3 Correct 18 ms 25600 KB Output is correct
4 Correct 19 ms 25600 KB Output is correct
5 Correct 18 ms 25600 KB Output is correct
6 Correct 19 ms 25688 KB Output is correct
7 Correct 18 ms 25600 KB Output is correct
8 Correct 18 ms 25600 KB Output is correct
9 Correct 20 ms 25600 KB Output is correct
10 Correct 21 ms 25592 KB Output is correct
11 Correct 18 ms 25600 KB Output is correct
12 Correct 19 ms 25632 KB Output is correct
13 Correct 19 ms 25728 KB Output is correct
14 Correct 19 ms 25600 KB Output is correct
15 Correct 18 ms 25600 KB Output is correct
16 Correct 19 ms 25600 KB Output is correct
17 Correct 20 ms 25600 KB Output is correct
18 Correct 18 ms 25600 KB Output is correct
19 Correct 20 ms 25600 KB Output is correct
20 Correct 32 ms 26752 KB Output is correct
21 Correct 31 ms 26752 KB Output is correct
22 Correct 31 ms 27000 KB Output is correct
23 Correct 30 ms 27008 KB Output is correct
24 Correct 35 ms 26872 KB Output is correct
25 Correct 20 ms 26880 KB Output is correct
26 Correct 36 ms 27004 KB Output is correct
27 Correct 25 ms 26624 KB Output is correct
28 Correct 27 ms 26752 KB Output is correct
29 Correct 29 ms 26880 KB Output is correct
30 Correct 31 ms 27008 KB Output is correct
31 Correct 28 ms 27008 KB Output is correct
32 Correct 30 ms 27008 KB Output is correct
33 Correct 31 ms 27008 KB Output is correct
34 Correct 420 ms 49076 KB Output is correct
35 Incorrect 464 ms 49016 KB Output isn't correct
36 Halted 0 ms 0 KB -

Subtask #4
0 / 8.0

# 결과 실행 시간 메모리 Grader output
1 Correct 19 ms 25600 KB Output is correct
2 Correct 19 ms 25600 KB Output is correct
3 Correct 18 ms 25600 KB Output is correct
4 Correct 19 ms 25600 KB Output is correct
5 Correct 18 ms 25600 KB Output is correct
6 Correct 19 ms 25688 KB Output is correct
7 Correct 18 ms 25600 KB Output is correct
8 Correct 18 ms 25600 KB Output is correct
9 Correct 20 ms 25600 KB Output is correct
10 Correct 21 ms 25592 KB Output is correct
11 Correct 18 ms 25600 KB Output is correct
12 Correct 19 ms 25632 KB Output is correct
13 Correct 19 ms 25728 KB Output is correct
14 Correct 19 ms 25600 KB Output is correct
15 Correct 18 ms 25600 KB Output is correct
16 Correct 19 ms 25600 KB Output is correct
17 Correct 20 ms 25600 KB Output is correct
18 Correct 18 ms 25600 KB Output is correct
19 Correct 20 ms 25600 KB Output is correct
20 Correct 32 ms 26752 KB Output is correct
21 Correct 31 ms 26752 KB Output is correct
22 Correct 31 ms 27000 KB Output is correct
23 Correct 30 ms 27008 KB Output is correct
24 Correct 35 ms 26872 KB Output is correct
25 Correct 20 ms 26880 KB Output is correct
26 Correct 36 ms 27004 KB Output is correct
27 Correct 25 ms 26624 KB Output is correct
28 Correct 27 ms 26752 KB Output is correct
29 Correct 29 ms 26880 KB Output is correct
30 Correct 31 ms 27008 KB Output is correct
31 Correct 28 ms 27008 KB Output is correct
32 Correct 30 ms 27008 KB Output is correct
33 Correct 31 ms 27008 KB Output is correct
34 Correct 420 ms 49076 KB Output is correct
35 Incorrect 464 ms 49016 KB Output isn't correct
36 Halted 0 ms 0 KB -

Subtask #5
0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Correct 424 ms 54256 KB Output is correct
2 Correct 913 ms 60152 KB Output is correct
3 Incorrect 810 ms 59932 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 555 ms 53740 KB Output is correct
2 Correct 690 ms 53612 KB Output is correct
3 Correct 734 ms 63088 KB Output is correct
4 Correct 687 ms 62532 KB Output is correct
5 Correct 654 ms 58352 KB Output is correct
6 Correct 99 ms 54888 KB Output is correct
7 Correct 749 ms 63088 KB Output is correct
8 Correct 154 ms 51828 KB Output is correct
9 Correct 300 ms 50928 KB Output is correct
10 Correct 328 ms 63212 KB Output is correct
11 Correct 520 ms 63852 KB Output is correct
12 Correct 485 ms 63724 KB Output is correct
13 Correct 753 ms 63088 KB Output is correct

Subtask #7
0 / 12.0

# 결과 실행 시간 메모리 Grader output
1 Correct 19 ms 25600 KB Output is correct
2 Correct 19 ms 25600 KB Output is correct
3 Correct 18 ms 25600 KB Output is correct
4 Correct 19 ms 25600 KB Output is correct
5 Correct 18 ms 25600 KB Output is correct
6 Correct 19 ms 25688 KB Output is correct
7 Correct 18 ms 25600 KB Output is correct
8 Correct 18 ms 25600 KB Output is correct
9 Correct 20 ms 25600 KB Output is correct
10 Correct 21 ms 25592 KB Output is correct
11 Correct 18 ms 25600 KB Output is correct
12 Correct 19 ms 25632 KB Output is correct
13 Correct 19 ms 25728 KB Output is correct
14 Correct 19 ms 25600 KB Output is correct
15 Correct 18 ms 25600 KB Output is correct
16 Correct 19 ms 25600 KB Output is correct
17 Correct 20 ms 25600 KB Output is correct
18 Correct 18 ms 25600 KB Output is correct
19 Correct 20 ms 25600 KB Output is correct
20 Correct 32 ms 26752 KB Output is correct
21 Correct 31 ms 26752 KB Output is correct
22 Correct 31 ms 27000 KB Output is correct
23 Correct 30 ms 27008 KB Output is correct
24 Correct 35 ms 26872 KB Output is correct
25 Correct 20 ms 26880 KB Output is correct
26 Correct 36 ms 27004 KB Output is correct
27 Correct 25 ms 26624 KB Output is correct
28 Correct 27 ms 26752 KB Output is correct
29 Correct 29 ms 26880 KB Output is correct
30 Correct 31 ms 27008 KB Output is correct
31 Correct 28 ms 27008 KB Output is correct
32 Correct 30 ms 27008 KB Output is correct
33 Correct 31 ms 27008 KB Output is correct
34 Correct 420 ms 49076 KB Output is correct
35 Incorrect 464 ms 49016 KB Output isn't correct
36 Halted 0 ms 0 KB -

Subtask #8
0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Correct 19 ms 25600 KB Output is correct
2 Correct 19 ms 25600 KB Output is correct
3 Correct 18 ms 25600 KB Output is correct
4 Correct 19 ms 25600 KB Output is correct
5 Correct 18 ms 25600 KB Output is correct
6 Correct 19 ms 25688 KB Output is correct
7 Correct 18 ms 25600 KB Output is correct
8 Correct 18 ms 25600 KB Output is correct
9 Correct 20 ms 25600 KB Output is correct
10 Correct 21 ms 25592 KB Output is correct
11 Correct 18 ms 25600 KB Output is correct
12 Correct 19 ms 25632 KB Output is correct
13 Correct 19 ms 25728 KB Output is correct
14 Correct 19 ms 25600 KB Output is correct
15 Correct 18 ms 25600 KB Output is correct
16 Correct 19 ms 25600 KB Output is correct
17 Correct 20 ms 25600 KB Output is correct
18 Correct 18 ms 25600 KB Output is correct
19 Correct 20 ms 25600 KB Output is correct
20 Correct 32 ms 26752 KB Output is correct
21 Correct 31 ms 26752 KB Output is correct
22 Correct 31 ms 27000 KB Output is correct
23 Correct 30 ms 27008 KB Output is correct
24 Correct 35 ms 26872 KB Output is correct
25 Correct 20 ms 26880 KB Output is correct
26 Correct 36 ms 27004 KB Output is correct
27 Correct 25 ms 26624 KB Output is correct
28 Correct 27 ms 26752 KB Output is correct
29 Correct 29 ms 26880 KB Output is correct
30 Correct 31 ms 27008 KB Output is correct
31 Correct 28 ms 27008 KB Output is correct
32 Correct 30 ms 27008 KB Output is correct
33 Correct 31 ms 27008 KB Output is correct
34 Correct 420 ms 49076 KB Output is correct
35 Incorrect 464 ms 49016 KB Output isn't correct
36 Halted 0 ms 0 KB -