oj.uz

답안 #245911

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
245911 2020-07-07T18:40:02 Z ajpiano Museum (CEOI17_museum) C++17
100 / 100
 655 ms 2728 KB 
#include <bits/stdc++.h>
#pragma GCC optimize("O3")

using namespace std;

#define FOR(a,b) for(int a=0;a<b;a++)
#define F0R(a,b,c) for(int a = b; a<=c; a++)
#define f first
#define s second
#define m0(x) memset(x,0,sizeof(x))
#define all(x) x.begin(), x.end()


typedef pair<int,int> pi;
typedef long long ll;
typedef vector<int> vi;
typedef vector<pi> vpi;

const int large = 1e4+1;

const int inf = 1e9;

int n,k,x;

vpi edges[large];

bool regcomp(const pi &a, const pi &b){
    if(a.f != b.f) return (a.f < b.f);
    else return (a.s > b.s);
}

bool greecomp(const pi &a, const pi &b){
    if(2*a.f-a.s != 2*b.f-b.s) return (2*a.f-a.s < 2*b.f-b.s);
    else return (a.f < b.f);
}


int dfs(int child, int parent, vpi &reg, vpi &greedy){
    int children = 1;
    int ptr = 0;
    vpi csize;
    vector<vpi> chilreg,chilgree;
    for(auto &a: edges[child]){
        if(a.f == parent) continue;
        chilreg.resize(ptr+1);
        chilgree.resize(ptr+1);
        int c = dfs(a.f,child,chilreg[ptr],chilgree[ptr]);
        for(auto &b: chilreg[ptr]){
            b.f += a.s;
            b.s += a.s;
        }
        for(auto &b: chilgree[ptr]){
            b.f += a.s;
            b.s += a.s;
        }
        children += c;
        csize.push_back({c,ptr});
        ptr++;
    }
    int nsz = min(children,k);
    reg.resize(nsz+1,{inf,0});
    greedy.resize(nsz+1,{inf,0});
    reg[1].f = 0;
    greedy[1].f = 0;
    sort(all(csize),greater<pi>());
    int chilcnt = 1;
    for(auto &a: csize){
        int c = a.f; ptr = a.s;
        int sz = min(c,k);
        for(int i = min(chilcnt,nsz-1); i >= 1; i--){
            F0R(j,1,sz){
                if(i+j> nsz) break;
                //reg
                pi b = {reg[i].f+chilreg[ptr][j].f,max(reg[i].s,chilreg[ptr][j].s)};
                reg[i+j]= min(reg[i+j],b,regcomp);
                //greedy
                greedy[i+j] = min(greedy[i+j],b,greecomp);
                b = {greedy[i].f+chilreg[ptr][j].f,max(greedy[i].s,chilreg[ptr][j].s)};
                greedy[i+j] = min(greedy[i+j],b,greecomp);
                b = {reg[i].f+chilgree[ptr][j].f,max(reg[i].s,chilgree[ptr][j].s)};
                greedy[i+j] = min(greedy[i+j],b,greecomp);
            }
        }
        chilcnt += c;
    }
    return children;
}

int main()
{
    ios_base::sync_with_stdio(0); cin.tie(0);
    cin >> n >> k >> x;
    FOR(i,n-1){
        int a,b,c; cin >> a >> b >> c;
        edges[a].push_back({b,c});
        edges[b].push_back({a,c});
    }
    vpi reg,greedy;
    dfs(x,0,reg,greedy);
    assert(2*greedy[k].f-greedy[k].s <= 2*reg[k].f-reg[k].s);
    cout << 2*greedy[k].f-greedy[k].s << "\n";
    return 0;
}

Subtask #1
20.0 / 20.0

# 결과 실행 시간 메모리 Grader output
1 Correct 5 ms 640 KB Output is correct
2 Correct 5 ms 512 KB Output is correct
3 Correct 5 ms 512 KB Output is correct
4 Correct 5 ms 640 KB Output is correct
5 Correct 5 ms 512 KB Output is correct

Subtask #2
25.0 / 25.0

# 결과 실행 시간 메모리 Grader output
1 Correct 24 ms 1152 KB Output is correct
2 Correct 21 ms 1152 KB Output is correct
3 Correct 23 ms 2304 KB Output is correct
4 Correct 22 ms 1664 KB Output is correct
5 Correct 22 ms 1152 KB Output is correct

Subtask #3
35.0 / 35.0

# 결과 실행 시간 메모리 Grader output
1 Correct 24 ms 1152 KB Output is correct
2 Correct 21 ms 1152 KB Output is correct
3 Correct 23 ms 2304 KB Output is correct
4 Correct 22 ms 1664 KB Output is correct
5 Correct 22 ms 1152 KB Output is correct
6 Correct 26 ms 1152 KB Output is correct
7 Correct 24 ms 2048 KB Output is correct
8 Correct 24 ms 2364 KB Output is correct
9 Correct 21 ms 1792 KB Output is correct
10 Correct 22 ms 1280 KB Output is correct

Subtask #4
20.0 / 20.0

# 결과 실행 시간 메모리 Grader output
1 Correct 5 ms 640 KB Output is correct
2 Correct 5 ms 512 KB Output is correct
3 Correct 5 ms 512 KB Output is correct
4 Correct 5 ms 640 KB Output is correct
5 Correct 5 ms 512 KB Output is correct
6 Correct 24 ms 1152 KB Output is correct
7 Correct 21 ms 1152 KB Output is correct
8 Correct 23 ms 2304 KB Output is correct
9 Correct 22 ms 1664 KB Output is correct
10 Correct 22 ms 1152 KB Output is correct
11 Correct 26 ms 1152 KB Output is correct
12 Correct 24 ms 2048 KB Output is correct
13 Correct 24 ms 2364 KB Output is correct
14 Correct 21 ms 1792 KB Output is correct
15 Correct 22 ms 1280 KB Output is correct
16 Correct 102 ms 1272 KB Output is correct
17 Correct 296 ms 1400 KB Output is correct
18 Correct 94 ms 1792 KB Output is correct
19 Correct 118 ms 2176 KB Output is correct
20 Correct 89 ms 1280 KB Output is correct
21 Correct 440 ms 2320 KB Output is correct
22 Correct 402 ms 1528 KB Output is correct
23 Correct 655 ms 2296 KB Output is correct
24 Correct 399 ms 1528 KB Output is correct
25 Correct 445 ms 2728 KB Output is correct