oj.uz

Submission #525251

# Submission time Handle Problem Language Result Execution time Memory
525251 2022-02-11T07:46:47 Z qwerasdfzxcl Mountains and Valleys (CCO20_day1problem3) C++14
2 / 25
 14 ms 12968 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){
    cyc.push_back(s);
    if (s==e) return 1;
    for (auto &v:adj[s]) if (v.v!=pa && on[v.i]){
        P.push_back(v.i);
        if (dfs0(v.v, e, s)) return 1;
        P.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){
        P.clear();
        assert(dfs0(e.v, e.w));

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

        for (auto &x:P){
            on[x] = 0, cur -= W[x];
            ans = min(ans, 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++;
                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:44:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   44 |     scanf("%d %d", &n, &m);
      |     ~~~~~^~~~~~~~~~~~~~~~~
Main.cpp:47:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   47 |         scanf("%d %d %d", &x, &y, &z);
      |         ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~

Subtask #1
0.0 / 1.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 11980 KB Output is correct
2 Incorrect 6 ms 11980 KB Output isn't correct
3 Halted 0 ms 0 KB -

Subtask #2
0.0 / 2.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 11980 KB Output is correct
2 Incorrect 6 ms 11980 KB Output isn't correct
3 Halted 0 ms 0 KB -

Subtask #3
2.0 / 2.0

# Verdict Execution time Memory Grader output
1 Correct 10 ms 12968 KB Output is correct
2 Correct 11 ms 12876 KB Output is correct
3 Correct 10 ms 12752 KB Output is correct
4 Correct 10 ms 12740 KB Output is correct
5 Correct 10 ms 12748 KB Output is correct
6 Correct 11 ms 12688 KB Output is correct
7 Correct 10 ms 12876 KB Output is correct
8 Correct 14 ms 12876 KB Output is correct
9 Correct 10 ms 12876 KB Output is correct
10 Correct 12 ms 12848 KB Output is correct
11 Correct 11 ms 12852 KB Output is correct
12 Correct 10 ms 12876 KB Output is correct
13 Correct 11 ms 12876 KB Output is correct
14 Correct 14 ms 12876 KB Output is correct

Subtask #4
0.0 / 6.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 11980 KB Output is correct
2 Incorrect 6 ms 11980 KB Output isn't correct
3 Halted 0 ms 0 KB -

Subtask #5
0.0 / 2.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 11980 KB Output is correct
2 Incorrect 6 ms 11980 KB Output isn't correct
3 Halted 0 ms 0 KB -

Subtask #6
0.0 / 3.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 11980 KB Output is correct
2 Incorrect 6 ms 11980 KB Output isn't correct
3 Halted 0 ms 0 KB -

Subtask #7
0.0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 11980 KB Output is correct
2 Incorrect 6 ms 11980 KB Output isn't correct
3 Halted 0 ms 0 KB -

Subtask #8
0.0 / 4.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 11980 KB Output is correct
2 Incorrect 6 ms 11980 KB Output isn't correct
3 Halted 0 ms 0 KB -