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Submission #525262

# Submission time Handle Problem Language Result Execution time Memory
525262 2022-02-11T08:30:54 Z qwerasdfzxcl Mountains and Valleys (CCO20_day1problem3) C++14
2 / 25
 24 ms 24260 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();
        cyc.clear();
        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:45:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   45 |     scanf("%d %d", &n, &m);
      |     ~~~~~^~~~~~~~~~~~~~~~~
Main.cpp:48:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   48 |         scanf("%d %d %d", &x, &y, &z);
      |         ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~

Subtask #1
0.0 / 1.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 12044 KB Output is correct
2 Correct 8 ms 11980 KB Output is correct
3 Correct 6 ms 11980 KB Output is correct
4 Correct 7 ms 12000 KB Output is correct
5 Runtime error 17 ms 24260 KB Execution killed with signal 6
6 Halted 0 ms 0 KB -

Subtask #2
0.0 / 2.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 12044 KB Output is correct
2 Correct 8 ms 11980 KB Output is correct
3 Correct 6 ms 11980 KB Output is correct
4 Correct 7 ms 12000 KB Output is correct
5 Runtime error 17 ms 24260 KB Execution killed with signal 6
6 Halted 0 ms 0 KB -

Subtask #3
2.0 / 2.0

# Verdict Execution time Memory Grader output
1 Correct 10 ms 12876 KB Output is correct
2 Correct 12 ms 12876 KB Output is correct
3 Correct 10 ms 12620 KB Output is correct
4 Correct 11 ms 12620 KB Output is correct
5 Correct 11 ms 12648 KB Output is correct
6 Correct 10 ms 12620 KB Output is correct
7 Correct 11 ms 12768 KB Output is correct
8 Correct 14 ms 12700 KB Output is correct
9 Correct 24 ms 12712 KB Output is correct
10 Correct 21 ms 12712 KB Output is correct
11 Correct 11 ms 12748 KB Output is correct
12 Correct 10 ms 12620 KB Output is correct
13 Correct 10 ms 12740 KB Output is correct
14 Correct 11 ms 12724 KB Output is correct

Subtask #4
0.0 / 6.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 12044 KB Output is correct
2 Correct 8 ms 11980 KB Output is correct
3 Correct 6 ms 11980 KB Output is correct
4 Correct 7 ms 12000 KB Output is correct
5 Runtime error 17 ms 24260 KB Execution killed with signal 6
6 Halted 0 ms 0 KB -

Subtask #5
0.0 / 2.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 12044 KB Output is correct
2 Correct 8 ms 11980 KB Output is correct
3 Correct 6 ms 11980 KB Output is correct
4 Correct 7 ms 12000 KB Output is correct
5 Runtime error 17 ms 24260 KB Execution killed with signal 6
6 Halted 0 ms 0 KB -

Subtask #6
0.0 / 3.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 12044 KB Output is correct
2 Correct 8 ms 11980 KB Output is correct
3 Correct 6 ms 11980 KB Output is correct
4 Correct 7 ms 12000 KB Output is correct
5 Runtime error 17 ms 24260 KB Execution killed with signal 6
6 Halted 0 ms 0 KB -

Subtask #7
0.0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 12044 KB Output is correct
2 Correct 8 ms 11980 KB Output is correct
3 Correct 6 ms 11980 KB Output is correct
4 Correct 7 ms 12000 KB Output is correct
5 Runtime error 17 ms 24260 KB Execution killed with signal 6
6 Halted 0 ms 0 KB -

Subtask #8
0.0 / 4.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 12044 KB Output is correct
2 Correct 8 ms 11980 KB Output is correct
3 Correct 6 ms 11980 KB Output is correct
4 Correct 7 ms 12000 KB Output is correct
5 Runtime error 17 ms 24260 KB Execution killed with signal 6
6 Halted 0 ms 0 KB -