Submission #99448

#	Time	Username	Problem	Language	Result	Execution time	Memory
99448		psmao	Commuter Pass (JOI18_commuter_pass)	C++14	0 / 100	94 ms	8612 KiB

commuter_pass

#include <bits/stdc++.h>
using namespace std;

#define fo(i,s,t) for(int i = s; i <= t; ++ i)
#define fd(i,s,t) for(int i = s; i >= t; -- i)
#define bf(i,s) for(int i = head[s]; i; i = e[i].next)
#define mp make_pair
#define fi first
#define se second
#define pii pair<int,int>
#define pb push_back
#define VI vector<int>
#define sf scanf
#define pf printf
#define fp freopen
#define SZ(x) ((int)(x).size())
#ifdef MPS
#define D(x...) printf(x)
#else
#define D(x...)
#endif
typedef long long ll;
typedef double db;
typedef unsigned long long ull;
const int inf = 1<<30;
const ll INF = 1ll<<59;
const db Inf = 1e20;
const db eps = 1e-9;

void gmax(int &a,int b){a = (a > b ? a : b);}
void gmin(int &a,int b){a = (a < b ? a : b);}

const int maxn = 100050;

int n, m, s, t, u, v, head[maxn], tot, pre[maxn];
struct edge{int next, to, w;}e[maxn<<1];
ll dist[maxn];
bool inq[maxn];

void add_edge(int u, int v, int w)
{
	e[tot] = (struct edge){head[u], v, w}; head[u] = tot++;
	e[tot] = (struct edge){head[v], u, w}; head[v] = tot++;
}
ll dijkstra(int s, int t)
{
	priority_queue<pii,vector<pii>,greater<pii> > pq;
	pq.push(mp(0, s));
	fo(i,1,n) dist[i] = INF;
	dist[s] = 0;
	while(!pq.empty())
	{
		int h = pq.top().se; pq.pop(); inq[h] = false;
		for(int i = head[h]; i != -1; i = e[i].next)
		{
			int v = e[i].to; 
			if(dist[v] > dist[h] + e[i].w)
			{
				dist[v] = dist[h] + e[i].w;
				pre[v] = i;
				if(!inq[v]) inq[v] = true, pq.push(mp(dist[v], v));
			}
		}
	}
	return dist[t];
}
void back_track(int t)
{
	if(t == s) return;
	e[pre[t]].w = 0;
	back_track(e[pre[t]^1].to);
}
int main()
{
	#ifdef MPS
		fp("1.in","r",stdin);
		fp("1.out","w",stdout);
	#endif
	sf("%d%d",&n,&m);
	sf("%d%d%d%d",&s,&t,&u,&v);
	memset(head, -1, sizeof(head));
	fo(i,1,m)
	{
		int u, v, w;
		sf("%d%d%d",&u,&v,&w);
		add_edge(u, v, w);
	}
	dijkstra(s, t);
	back_track(t);
	pf("%lld\n",dijkstra(u, v));
	return 0;
}

Compilation message (stderr)

commuter_pass.cpp: In function 'int main()':
commuter_pass.cpp:79:4: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  sf("%d%d",&n,&m);
    ^
commuter_pass.cpp:80:4: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  sf("%d%d%d%d",&s,&t,&u,&v);
    ^
commuter_pass.cpp:85:5: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   sf("%d%d%d",&u,&v,&w);
     ^

• Subtask 1: 0 / 16
• Subtask 2: 0 / 15
• Subtask 3: 0 / 24
• Subtask 4: 0 / 45