Submission #526726

#	Time	Username	Problem	Language	Result	Execution time	Memory
526726		cpp219	Designated Cities (JOI19_designated_cities)	C++14	100 / 100	326 ms	42680 KiB

designated_cities

#include <bits/stdc++.h>
#define ll long long
#define ld double
#define fs first
#define sc second
#define debug(y) cout<<y,exit(0)
using namespace std;
typedef pair<ll,ll> LL;
const ll N = 2e5 + 9;
const ll inf = 1e18 + 7;

ll n,sum[N],res[N],deg[N];

struct edge{
    ll v,c,d;
};
vector<edge> g[N];

void dfs(ll u,ll p){
    for (auto i : g[u]) if (i.v != p){
        dfs(i.v,u);
        sum[u] += sum[i.v] + i.c;
    }
}
void dfs1(ll u,ll p,ll s){
    res[1] = min(res[1],s);
    for (auto i : g[u])
        if (i.v != p) dfs1(i.v,u,s - i.c + i.d);
}

int main(){
    ios_base::sync_with_stdio(NULL); cin.tie(0); cout.tie(0);
    #define task "tst"
    if (fopen(task".inp","r")){
        freopen(task".inp","r",stdin);
        //freopen(task".out","w",stdout);
    }
    cin>>n;
    for (ll i = 1;i < n;i++){
        ll u,v,c,d; cin>>u>>v>>c>>d;
        g[u].push_back({v,c,d}); g[v].push_back({u,d,c});
        deg[u]++; deg[v]++;
    }
    res[1] = inf;
    dfs(1,0); dfs1(1,0,sum[1]);
    priority_queue<LL,vector<LL>,greater<LL>> pq;
    for (ll i = 1;i <= n;i++)
        if (g[i].size() == 1) pq.push({g[i][0].d,i});
    //return 0;
    while(pq.size() > 2){
        LL now = pq.top(); pq.pop();
        ll nxt = -1;
        for (auto i : g[now.sc]){
            if (deg[i.v] > 1){
                deg[i.v]--;
                if (deg[i.v] == 1) nxt = i.v;
                else res[pq.size()] = res[pq.size() + 1] + now.fs;
            }
        }
        if (nxt > 0){
            for (auto i : g[nxt])
                if (deg[i.v] > 1) pq.push({now.fs + i.d,nxt});
        }
    }
    ll Q; cin>>Q;
    while(Q--){
        ll x; cin>>x; cout<<res[x]<<"\n";
    }
}

/* stuff you should look for
	* int overflow, array bounds
	* special cases (n=1?)
	* do smth instead of nothing and stay organized
	* WRITE STUFF DOWN
	* DON'T GET STUCK ON ONE APPROACH
*/

Compilation message (stderr)

designated_cities.cpp: In function 'int main()':
designated_cities.cpp:35:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   35 |         freopen(task".inp","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 6 / 6
• Subtask 2: 7 / 7
• Subtask 3: 9 / 9
• Subtask 4: 17 / 17
• Subtask 5: 17 / 17
• Subtask 6: 44 / 44