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Submission #525269

# Submission time Handle Problem Language Result Execution time Memory
525269 2022-02-11T08:46:58 Z qwerasdfzxcl Mountains and Valleys (CCO20_day1problem3) C++14
2 / 25
 15 ms 12876 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();
        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();
        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

# Verdict Execution time Memory Grader output
1 Correct 6 ms 11980 KB Output is correct
2 Incorrect 6 ms 12064 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 12064 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 12 ms 12876 KB Output is correct
2 Correct 11 ms 12748 KB Output is correct
3 Correct 11 ms 12620 KB Output is correct
4 Correct 13 ms 12672 KB Output is correct
5 Correct 11 ms 12620 KB Output is correct
6 Correct 15 ms 12620 KB Output is correct
7 Correct 12 ms 12748 KB Output is correct
8 Correct 14 ms 12748 KB Output is correct
9 Correct 10 ms 12744 KB Output is correct
10 Correct 11 ms 12620 KB Output is correct
11 Correct 11 ms 12620 KB Output is correct
12 Correct 11 ms 12748 KB Output is correct
13 Correct 11 ms 12736 KB Output is correct
14 Correct 10 ms 12712 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 12064 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 12064 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 12064 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 12064 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 12064 KB Output isn't correct
3 Halted 0 ms 0 KB -