Submission #872182

#	Time	Username	Problem	Language	Result	Execution time	Memory
872182		SalihSahin	Svjetlo (COCI20_svjetlo)	C++14	0 / 110	149 ms	54588 KiB

svjetlo

#include<bits/stdc++.h>
#define pb push_back
#define mp make_pair
#define int long long 
using namespace std;

const int N = 5e5 + 5;
const int mod = 1e9+7;
const int inf = 1e18 + 10;
const int L = 20 * 20 * 20;

vector<int> in(N), adj[N];
vector<int> arr;

void dfs(int node, int par){
    arr.pb(node);
    for(auto itr: adj[node]){
        if(itr != par){
            dfs(itr, node);
        }
    }
}

int32_t main(){
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    int n;
    cin>>n;
    string s;
    cin>>s;
    for(int i = 0; i < n-1; i++){
        int a, b;
        cin>>a>>b;
        in[a]++;
        in[b]++;
        adj[a].pb(b);
        adj[b].pb(a);
    }
    int uc = 0;
    for(int i = 1; i <= n; i++){
        if(in[i] == 1){
            uc = i;
            break;
        }
    }

    dfs(uc, uc);
    int first = n, last = 0;
    vector<int> pre(n+1);
    vector<int> tree(n);
    for(int i = 0; i < n; i++){
        tree[i] = s[arr[i] - 1] - '0';
        if(tree[i] == 0){
            first = min(first, i);
            last = max(last, i);
        }
        pre[i+1] = pre[i] + (tree[i] == 0);
    }
    int ans = (n - first - (n - 1 - last) - pre[n]) * 2 + pre[n];
    cout<<ans<<endl;
    return 0;
}

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