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Submission #525259

# Submission time Handle Problem Language Result Execution time Memory
525259 2022-02-11T08:17:06 Z qwerasdfzxcl Mountains and Valleys (CCO20_day1problem3) C++14
2 / 25
 16 ms 24276 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++;
                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 7 ms 11980 KB Output is correct
2 Correct 7 ms 11984 KB Output is correct
3 Correct 7 ms 12032 KB Output is correct
4 Correct 7 ms 12052 KB Output is correct
5 Runtime error 16 ms 24276 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 7 ms 11980 KB Output is correct
2 Correct 7 ms 11984 KB Output is correct
3 Correct 7 ms 12032 KB Output is correct
4 Correct 7 ms 12052 KB Output is correct
5 Runtime error 16 ms 24276 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 13 ms 12988 KB Output is correct
2 Correct 12 ms 12860 KB Output is correct
3 Correct 11 ms 12764 KB Output is correct
4 Correct 12 ms 12788 KB Output is correct
5 Correct 11 ms 12704 KB Output is correct
6 Correct 12 ms 12772 KB Output is correct
7 Correct 12 ms 12884 KB Output is correct
8 Correct 11 ms 12876 KB Output is correct
9 Correct 10 ms 12876 KB Output is correct
10 Correct 11 ms 12764 KB Output is correct
11 Correct 11 ms 12836 KB Output is correct
12 Correct 11 ms 12840 KB Output is correct
13 Correct 11 ms 12760 KB Output is correct
14 Correct 11 ms 12840 KB Output is correct

Subtask #4
0.0 / 6.0

# Verdict Execution time Memory Grader output
1 Correct 7 ms 11980 KB Output is correct
2 Correct 7 ms 11984 KB Output is correct
3 Correct 7 ms 12032 KB Output is correct
4 Correct 7 ms 12052 KB Output is correct
5 Runtime error 16 ms 24276 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 7 ms 11980 KB Output is correct
2 Correct 7 ms 11984 KB Output is correct
3 Correct 7 ms 12032 KB Output is correct
4 Correct 7 ms 12052 KB Output is correct
5 Runtime error 16 ms 24276 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 7 ms 11980 KB Output is correct
2 Correct 7 ms 11984 KB Output is correct
3 Correct 7 ms 12032 KB Output is correct
4 Correct 7 ms 12052 KB Output is correct
5 Runtime error 16 ms 24276 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 7 ms 11980 KB Output is correct
2 Correct 7 ms 11984 KB Output is correct
3 Correct 7 ms 12032 KB Output is correct
4 Correct 7 ms 12052 KB Output is correct
5 Runtime error 16 ms 24276 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 7 ms 11980 KB Output is correct
2 Correct 7 ms 11984 KB Output is correct
3 Correct 7 ms 12032 KB Output is correct
4 Correct 7 ms 12052 KB Output is correct
5 Runtime error 16 ms 24276 KB Execution killed with signal 6
6 Halted 0 ms 0 KB -