Submission #143791

#	Time	Username	Problem	Language	Result	Execution time	Memory
143791		cheetose	Telegraph (JOI16_telegraph)	C++11	100 / 100	79 ms	16212 KiB

telegraph

#include<cstdio>
#include<cstdlib>
#include<iostream>
#include<vector>
#include<queue>
#include<bitset>
#include<string>
#include<stack>
#include<set>
#include<unordered_set>
#include<map>
#include<unordered_map>
#include<cstring>
#include<complex>
#include<cmath>
#include<iomanip>
#include<numeric>
#include<algorithm>
#include<list>
#include<functional>
#include<cassert>
#define mp make_pair
#define pb push_back
#define X first
#define Y second
#define y0 y12
#define y1 y22
#define INF 987654321987654321
#define PI 3.141592653589793238462643383279502884
#define fup(i,a,b,c) for(int (i)=(a);(i)<=(b);(i)+=(c))
#define fdn(i,a,b,c) for(int (i)=(a);(i)>=(b);(i)-=(c))
#define MEM0(a) memset((a),0,sizeof(a));
#define MEM_1(a) memset((a),-1,sizeof(a));
#define ALL(a) a.begin(),a.end()
#define SYNC ios_base::sync_with_stdio(false);cin.tie(0)
using namespace std;
typedef long long ll;
typedef long double ld;
typedef double db;
typedef unsigned int uint;
typedef unsigned long long ull;
typedef pair<int, int> Pi;
typedef pair<ll, ll> Pll;
typedef pair<ld, ld> Pd;
typedef vector<int> Vi;
typedef vector<ll> Vll;
typedef vector<double> Vd;
typedef vector<Pi> VPi;
typedef vector<Pll> VPll;
typedef vector<Pd> VPd;
typedef tuple<int, int, int> iii;
typedef tuple<int,int,int,int> iiii;
typedef tuple<ll, ll, ll> LLL;
typedef vector<iii> Viii;
typedef vector<LLL> VLLL;
typedef complex<double> base;
const ll MOD = 1000000007;
ll POW(ll a, ll b, ll MMM = MOD) {ll ret=1; for(;b;b>>=1,a=(a*a)%MMM)if(b&1)ret=(ret*a)% MMM; return ret; }
ll gcd(ll a, ll b) { return b ? gcd(b, a%b) : a; }
ll lcm(ll a, ll b) { if (a == 0 || b == 0)return a + b; return a*(b / gcd(a, b)); }
int dx[] = { 0,1,0,-1,1,1,-1,-1 }, dy[] = { 1,0,-1,0,1,-1,1,-1 };

int n;
int a[100001],c[100001],d[100001];
bool cc[100001];
int chk[100001];
vector<Vi> V;
Vi v[100001];
void dfs1(Vi &v,int x,int c)
{
	v.pb(x);
	chk[x]=c;
	if(chk[a[x]])
	{
		if(!cc[a[x]] && chk[a[x]]==c)
		{
			Vi st;
			while(1)
			{
				int t=v.back();
				v.pop_back();
				st.pb(t);
				if(t==a[x])break;
			}
			for(int &tt:st)cc[tt]=1;
			reverse(ALL(st));
			V.pb(st);
		}
	}
	else dfs1(v,a[x],c);
}
ll ans;
void dfs2(int N)
{
	ll t=0;
	for(int next:v[N])
	{
		dfs2(next);
		d[N]=max(d[N],c[next]);
		t+=c[next];
	}
	ans+=t-d[N];
}
int main() {
	scanf("%d",&n);
	fup(i,1,n,1)scanf("%d%d",a+i,c+i);
	fup(i,1,n,1)
	{
		if(!chk[i])
		{
			Vi v;
			dfs1(v,i,i);
		}
	}
	bool ok = 1;
	fup(i,1,n,1)
		if(!cc[i])
		{
			ok=0;
			v[a[i]].pb(i);
		}
	if(ok && V.size()==1)return !printf("0");
	fup(i,1,n,1)if(cc[i])dfs2(i);
	for(auto &vv:V)
	{
		ll mn=INF,t=0;
		int N=vv.size();
		int y=vv[N-1];
		fup(i,0,N-1,1)
		{
			t+=min(c[y],d[vv[i]]);
			y=vv[i];
		}
		fup(i,0,N-1,1)
		{
			t-=min(c[y],d[vv[i]]);
			mn=min(mn,t+c[y]);
			t+=min(c[y],d[vv[i]]);
			y=vv[i];
		}
		ans += mn;
	}
	printf("%lld",ans);
}

Compilation message (stderr)

telegraph.cpp: In function 'int main()':
telegraph.cpp:105:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&n);
  ~~~~~^~~~~~~~~
telegraph.cpp:106:19: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  fup(i,1,n,1)scanf("%d%d",a+i,c+i);
              ~~~~~^~~~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 30 / 30
• Subtask 3: 30 / 30
• Subtask 4: 30 / 30