Submission #1095289

#	Time	Username	Problem	Language	Result	Execution time	Memory
1095289		andrewp	Paths (BOI18_paths)	C++14	0 / 100	128 ms	31316 KiB

paths

//Dedicated to my love, ivaziva
#pragma GCC optimize("Ofast") 
#include <bits/stdc++.h> 
using namespace std;  

#define int long long 
 
using pii = pair<int, int>;
using ll = int64_t; 
 
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define dbg(x) cerr<<#x<<": "<<x<<'\n';  
#define dbga(A,l_,r_){for(int i_=l_;i_<=r_;i_++)cerr<<A[i_]<<' ';cerr<<'\n';}
#define dbgv(a_){for(auto x_:a_) cerr<<x_<<' ';cerr<<'\n';}   

const int N = 3e5 + 20;
int n, m, k, a[N], ans1, ans2;
vector<int> g[N];
bool was[N];

void dfs(int x) {
    was[x] = true; 
    int f = 0, s = 0, t = 0;
    for (int u : g[x]) {
        if (a[u] == 1) {
            f++;
        } else if (a[u] == 2) {
            s++;
        } else {
            t++;
        }
        if (!was[u]) { 
            dfs(u);
        }
    }   
    if (a[x] == 1) {
        ans1 += 2 * (s * t); 
        ans2 += s;  
        ans2 += t; 
    } else if (a[x] == 2) {
        ans1 += 2 * (f * t); 
        ans2 += f;
        ans2 += t;  
    } else { 
        ans1 += 2 * (f * s);  
        ans2 += f; 
        ans2 += s; 
    }  
}

int32_t main()  {
    ios::sync_with_stdio(false); cin.tie(nullptr);  
    cout.tie(nullptr); cerr.tie(nullptr);

    cin >> n >> m >> k;
    for (int i = 1; i <= n; i++) {
        cin >> a[i];
        was[i] = false;
    }
    for (int i = 0; i < m; i++) {
        int u, v;
        cin >> u >> v;
        g[u].push_back(v);
        g[v].push_back(u);
    }
    ans1 = 0, ans2 = 0;
    dfs(1);    
    if (k == 1) {
        cout << 0 << '\n';
    } else if (k == 2) {
        cout << ans2 << '\n'; 
    } else if (k == 3) {
        cout << ans1 + ans2 << '\n';
    } 
    return 0;
}

• Subtask 1: 0 / 23
• Subtask 2: 0 / 20
• Subtask 3: 0 / 27
• Subtask 4: 0 / 30