Submission #410553

#	Time	Username	Problem	Language	Result	Execution time	Memory
410553		Richw818	Traffic (IOI10_traffic)	C++17	100 / 100	1339 ms	170820 KiB

traffic

/*
 *  Written by: Richw818
 *  Lang: C++17
 *  main.cpp
 */
#include <bits/stdc++.h>
using namespace std;
//Macros
#define ll long long
#define ull unsigned long long
#define uint unsigned int
#define pb push_back
#define pf push_front
#define eb emplace_back
#define ef emplace_front
#define str string
#define fi first
#define se second
#define REP(i, n) for(int i = 0; i < (int)n; ++i)
#define sz(a) (int)(a.size())
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
//IO
template<class H, class T> void read(pair<H, T> &p);
template<class T> void read(vector<T>& v);
template<class T> void read(T& t){
    cin >> t;
}
template<class H, class... T> void read(H& h, T&... t){
    read(h);
    read(t...);
}
template<class T> void read(vector<T>& v){
    for(auto &t : v)
        read(t);
}
template<class H, class T> void read(pair<H, T> &p){
    read(p.fi, p.se);
}
void setIn(str s){
    freopen(s.c_str(), "r", stdin);
}
void setOut(str s){
    freopen(s.c_str(), "w", stdout);
}
void setIO(str s = ""){
    if(!sz(s))
        return;
    setIn(s+".in");
    setOut(s+".out");
}
//Debug
void __print(int x) {cerr << x;}
void __print(long x) {cerr << x;}
void __print(long long x) {cerr << x;}
void __print(unsigned x) {cerr << x;}
void __print(unsigned long x) {cerr << x;}
void __print(unsigned long long x) {cerr << x;}
void __print(float x) {cerr << x;}
void __print(double x) {cerr << x;}
void __print(long double x) {cerr << x;}
void __print(char x) {cerr << '\'' << x << '\'';}
void __print(const char *x) {cerr << '\"' << x << '\"';}
void __print(const string &x) {cerr << '\"' << x << '\"';}
void __print(bool x) {cerr << (x ? "true" : "false");}

template<typename T, typename V>
void __print(const pair<T, V> &x) {cerr << '{'; __print(x.first); cerr << ','; __print(x.second); cerr << '}';}
template<typename T>
void __print(const T &x) {int f = 0; cerr << '{'; for (auto &i: x) cerr << (f++ ? "," : ""), __print(i); cerr << "}";}
void _print() {cerr << "]\n";}
template <typename T, typename... V>
void _print(T t, V... v) {__print(t); if (sizeof...(v)) cerr << ", "; _print(v...);}
template<class H, class... T> void dbg(H& h, T&... t){
    dbg(h);
    dbg(t...);
}
#ifndef ONLINE_JUDGE
#define dbg(x...) cerr << "[" << #x << "] = ["; _print(x);
#else
#define dbg(x...)
#endif
//Constants
ll MODS[2] = {1000000007, 998244353};
const ll MOD = MODS[0];
const ll INF = (ll)1e18;
const double PI = acos(-1.0);
const int MAXN = (int)1e6+7;
//Code
vector<int> pop;
vector<int> tree[MAXN];
int cong[MAXN];
bitset<MAXN> vis;
int traff = INT_MAX, city = -1;
void dfs1(int n){
    vis[n] = true;
    cong[n] += pop[n];
    for(int adj : tree[n]){
        if(!vis[adj]){
            dfs1(adj);
            cong[n] += cong[adj];
        }
    }
}
void dfs2(int n, int x){
    vis[n] = true;
    int curr = x;
    for(int adj : tree[n]){
        if(!vis[adj]){
            dfs2(adj, x + cong[n] - cong[adj]);
            curr = max(curr, cong[adj]);
        }
    }
    if(curr < traff){
        traff = curr;
        city = n;
    }
}
void solve();
int LocateCentre(int n, int p[], int d[], int s[]){
    pop.resize(n);
    REP(i, n)
        pop[i] = p[i];
    REP(i, n-1){
        int dn = d[i];
        int sn = s[i];
        tree[dn].eb(sn);
        tree[sn].eb(dn);
    }
    solve();
    return city;
}
void solve(){
    dfs1(0);
    vis.reset();
    dfs2(0, 0);
}
//int main(){
//    setIO();
//    ios_base::sync_with_stdio(false);
//    cin.tie(nullptr);
//    solve();
//    return 0;
//}
/* 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)

traffic.cpp: In function 'void setIn(std::string)':
traffic.cpp:41:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   41 |     freopen(s.c_str(), "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
traffic.cpp: In function 'void setOut(std::string)':
traffic.cpp:44:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   44 |     freopen(s.c_str(), "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 25 / 25
• Subtask 2: 25 / 25
• Subtask 3: 25 / 25
• Subtask 4: 25 / 25