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답안 #525271

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
525271 2022-02-11T08:48:08 Z qwerasdfzxcl Mountains and Valleys (CCO20_day1problem3) C++14
2 / 25
 16 ms 24200 KB 
#include <bits/stdc++.h>

typedef long long ll;
using namespace std;
struct Edge{
    int v, w, i;
    Edge(){}
    Edge(int _v, int _w, int _i): v(_v), w(_w), i(_i) {}
};
vector<Edge> adj[500500];
int on[2002000], W[2002000], dist[500500];
vector<Edge> E;

vector<int> P, cyc;
bool dfs0(int s, int e, int pa = -1){
    if (s==e) return 1;
    for (auto &v:adj[s]) if (v.v!=pa && on[v.i]){
        P.push_back(v.i);
        cyc.push_back(v.i);
        if (dfs0(v.v, e, s)) return 1;
        P.pop_back();
        cyc.pop_back();
    }
    return 0;
}

void dfs(int s, int pa = -1, int w = 0){
    if (pa==-1) dist[s] = 0;
    else dist[s] = dist[pa] + w;
    for (auto &v:adj[s]) if (v.v!=pa && on[v.i]) dfs(v.v, s, v.w);
}

int cur = 0, ans = 1e9, m;
int calc(int s, int n){
    fill(dist, dist+n, 0);
    dfs(s);
    if (*max_element(dist, dist+n)==0) return 0;

    dfs(max_element(dist, dist+n)-dist);

    return *max_element(dist, dist+n);
}

int main(){
    int n;
    scanf("%d %d", &n, &m);
    for (int i=1;i<=m;i++){
        int x, y, z;
        scanf("%d %d %d", &x, &y, &z);
        adj[x].emplace_back(y, z, i);
        adj[y].emplace_back(x, z, i);
        W[i] = z;

        if (z==1) on[i] = 1, cur++;
        else E.emplace_back(x, y, i);
    }

    ans = min(ans, cur*2 - calc(0, n));

    if (n>500) {printf("%d\n", ans); return 0;}

    for (auto &e:E){
        //printf(" %d %d\n", e.v, e.w);
        P.clear();
        cyc.clear();
        cyc.push_back(e.v);
        assert(dfs0(e.v, e.w));

        on[e.i] = 1, cur += W[e.i];

        int tval = 1e9;
        for (auto &x:P){
            on[x] = 0, cur -= W[x];
            ans = min(ans, cur*2 - calc(0, n));
            tval = min(tval, cur*2 - calc(0, n));
            on[x] = 1, cur += W[x];
        }

        ///cycle
        on[e.i] = 0;
        vector<int> deep;

        int len = W[e.i] + P.size();

        for (auto &x:P) on[x] = 0;
        for (auto &x:cyc){
            fill(dist, dist+n, 0);
            dfs(x);
            deep.push_back(*max_element(dist, dist+n));
            ans = min(ans, cur*2-len-calc(x, n));
            //printf("%d: %d\n", x, calc(x, n));
            //for (int i=1;i<=9;i++) printf("%d", on[i]);
            //printf("\n");
        }


        for (int i=0;i<(int)cyc.size();i++){
            int clen = 0;
            for (int j=i+1;j<(int)cyc.size();j++){
                clen = j-i;
                assert(cur*2 - (max(clen, len-clen) + deep[i] + deep[j]) >= tval);
                ans = min(ans, cur*2 - (max(clen, len-clen) + deep[i] + deep[j]));
            }
        }

        ///

        for (auto &x:P) on[x] = 1;

        on[e.i] = 0, cur -= W[e.i];
    }

    printf("%d\n", ans);
    return 0;
}

Compilation message

Main.cpp: In function 'int main()':
Main.cpp:46:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   46 |     scanf("%d %d", &n, &m);
      |     ~~~~~^~~~~~~~~~~~~~~~~
Main.cpp:49:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   49 |         scanf("%d %d %d", &x, &y, &z);
      |         ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~

Subtask #1
0.0 / 1.0

# 결과 실행 시간 메모리 Grader output
1 Correct 7 ms 11980 KB Output is correct
2 Correct 7 ms 11980 KB Output is correct
3 Correct 7 ms 11980 KB Output is correct
4 Correct 7 ms 11980 KB Output is correct
5 Runtime error 16 ms 24200 KB Execution killed with signal 6
6 Halted 0 ms 0 KB -

Subtask #2
0.0 / 2.0

# 결과 실행 시간 메모리 Grader output
1 Correct 7 ms 11980 KB Output is correct
2 Correct 7 ms 11980 KB Output is correct
3 Correct 7 ms 11980 KB Output is correct
4 Correct 7 ms 11980 KB Output is correct
5 Runtime error 16 ms 24200 KB Execution killed with signal 6
6 Halted 0 ms 0 KB -

Subtask #3
2.0 / 2.0

# 결과 실행 시간 메모리 Grader output
1 Correct 12 ms 12876 KB Output is correct
2 Correct 12 ms 12752 KB Output is correct
3 Correct 13 ms 12692 KB Output is correct
4 Correct 12 ms 12636 KB Output is correct
5 Correct 11 ms 12680 KB Output is correct
6 Correct 12 ms 12620 KB Output is correct
7 Correct 10 ms 12748 KB Output is correct
8 Correct 10 ms 12748 KB Output is correct
9 Correct 10 ms 12780 KB Output is correct
10 Correct 10 ms 12668 KB Output is correct
11 Correct 10 ms 12620 KB Output is correct
12 Correct 10 ms 12620 KB Output is correct
13 Correct 11 ms 12620 KB Output is correct
14 Correct 11 ms 12752 KB Output is correct

Subtask #4
0.0 / 6.0

# 결과 실행 시간 메모리 Grader output
1 Correct 7 ms 11980 KB Output is correct
2 Correct 7 ms 11980 KB Output is correct
3 Correct 7 ms 11980 KB Output is correct
4 Correct 7 ms 11980 KB Output is correct
5 Runtime error 16 ms 24200 KB Execution killed with signal 6
6 Halted 0 ms 0 KB -

Subtask #5
0.0 / 2.0

# 결과 실행 시간 메모리 Grader output
1 Correct 7 ms 11980 KB Output is correct
2 Correct 7 ms 11980 KB Output is correct
3 Correct 7 ms 11980 KB Output is correct
4 Correct 7 ms 11980 KB Output is correct
5 Runtime error 16 ms 24200 KB Execution killed with signal 6
6 Halted 0 ms 0 KB -

Subtask #6
0.0 / 3.0

# 결과 실행 시간 메모리 Grader output
1 Correct 7 ms 11980 KB Output is correct
2 Correct 7 ms 11980 KB Output is correct
3 Correct 7 ms 11980 KB Output is correct
4 Correct 7 ms 11980 KB Output is correct
5 Runtime error 16 ms 24200 KB Execution killed with signal 6
6 Halted 0 ms 0 KB -

Subtask #7
0.0 / 5.0

# 결과 실행 시간 메모리 Grader output
1 Correct 7 ms 11980 KB Output is correct
2 Correct 7 ms 11980 KB Output is correct
3 Correct 7 ms 11980 KB Output is correct
4 Correct 7 ms 11980 KB Output is correct
5 Runtime error 16 ms 24200 KB Execution killed with signal 6
6 Halted 0 ms 0 KB -

Subtask #8
0.0 / 4.0

# 결과 실행 시간 메모리 Grader output
1 Correct 7 ms 11980 KB Output is correct
2 Correct 7 ms 11980 KB Output is correct
3 Correct 7 ms 11980 KB Output is correct
4 Correct 7 ms 11980 KB Output is correct
5 Runtime error 16 ms 24200 KB Execution killed with signal 6
6 Halted 0 ms 0 KB -