Submission #82236

#	Time	Username	Problem	Language	Result	Execution time	Memory
82236		AngelKnows	Cities (BOI16_cities)	C++14	100 / 100	1564 ms	32024 KiB

cities

#include <bits/stdc++.h>
using namespace std;
#define FOR(i,n) for (int i=1;i<=n;i++)
#define REP(i,a,b) for (int i=a;i<=b;i++)
 
#define pb push_back
#define fi first
#define se second
#define pi pair<int,int>
#define mp make_pair
#define sz(x) ((int)(x).size())
 
typedef long long ll;

const int inf=0x3f3f3f3f;
const ll linf=1e18;
const int N=100000+10;
const int M=200000+10;
const double eps=1e-5;
const int mo=1e9+7;

int n,k,m;
int a[6];
int x,y,w;
struct edge {
	int to,nxt;
	ll w;
} e[2*M];
int tot;
int head[N];

ll d[6][N];
int id[6][6];
ll f[11][N];

struct node {
	int x;
	ll v;
	bool operator<(node a) const {
		return v>a.v;
	}
};
priority_queue<node> pq;


ll ans=linf;

void insert(int x,int y,int w) {
	e[++tot].to=y,e[tot].w=w,e[tot].nxt=head[x],head[x]=tot;
	e[++tot].to=x,e[tot].w=w,e[tot].nxt=head[y],head[y]=tot;
}
void Dijkstra() {
	FOR(i,k) FOR(j,n) d[i][j]=linf;
	FOR(i,k) {
		d[i][a[i]]=0;
		pq.push(node{a[i],0});
		node u;
		int t,y,w;
		while (!pq.empty()) {
			u=pq.top();
			pq.pop();
			if (u.v>d[i][u.x]) continue;
			t=u.x;
			for (int j=head[t];j;j=e[j].nxt) {
				y=e[j].to,w=e[j].w;
				if (d[i][t]+w<d[i][y]) {
					d[i][y]=d[i][t]+w;
					pq.push(node{y,d[i][y]});
				}
			}
		}
	}
	int cnt=0;
	FOR(i,k) REP(j,i+1,k) id[i][j]=++cnt; 
	FOR(i,10) FOR(j,n) f[i][j]=linf;
	FOR(i,k) REP(j,i+1,k) {
		int num=id[i][j];
		//FOR(x,n) if (d[i][x]+d[j][x]==d[i][a[j]]) {
		FOR(x,n) {
			f[num][x]=d[i][x]+d[j][x];
			pq.push(node{x,f[num][x]});
		}
		node u;
		int t,y,w;
		while (!pq.empty()) {
			u=pq.top();
			pq.pop();
			if (u.v>f[num][u.x]) continue;
			t=u.x;
			for (int j=head[t];j;j=e[j].nxt) {
				y=e[j].to,w=e[j].w;
				if (f[num][t]+w<f[num][y]) {
					f[num][y]=f[num][t]+w;
					pq.push(node{y,f[num][y]});
				}
			}
		}
	}
}
int main() {
 
    std::ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);

    //freopen("in.txt","r",stdin);
    //freopen("out.txt","w",stdout);
    
    //注意你会爆int，你还没改！ 
    
    scanf("%d %d %d",&n,&k,&m);
    FOR(i,k) scanf("%d",&a[i]);
    FOR(i,m) {
    	scanf("%d %d %d",&x,&y,&w);
    	insert(x,y,w);
	}
	Dijkstra();
	if (k==2) {
		ans=d[1][a[2]];
	} else if (k==3) {
		FOR(i,n) {
			ans=min(ans,d[1][i]+d[2][i]+d[3][i]);
		}
	} else if (k==4) {
		ll res=0;
		FOR(i,k) REP(j,i+1,k) FOR(x,n) {
			res=f[id[i][j]][x];
			int tt=0,tt2=0;
			FOR(l,k) if (l!=i&&l!=j) {
				res+=d[l][x];
				if (tt) tt2=d[l][x];
				else tt=d[l][x];
			}
			//cout<<i<<" "<<j<<" "<<x<<" "<<f[id[i][j]][x]<<" "<<tt<<" "<<tt2<<" "<<res<<endl;
			ans=min(ans,res);
		}
	} else {
		ll res=0;
		int p1=0,p2=0;
		FOR(i,k) REP(j,i+1,k) FOR(x,n) {
			FOR(l,k) if (l!=i&&l!=j) {
				res=f[id[i][j]][x];
				p1=p2=0;
				FOR(r,k) if (r!=i&&r!=j&&r!=l) {
					if (p1) p2=r;
					else p1=r;
				}
				res+=d[l][x];
				res+=f[id[p1][p2]][x];
				ans=min(ans,res);
			}
		}
	}
	printf("%lld\n",ans);
	return 0;
}

Compilation message (stderr)

cities.cpp: In function 'int main()':
cities.cpp:128:13: warning: variable 'tt2' set but not used [-Wunused-but-set-variable]
    int tt=0,tt2=0;
             ^~~
cities.cpp:111:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d %d %d",&n,&k,&m);
     ~~~~~^~~~~~~~~~~~~~~~~~~~~
cities.cpp:112:19: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     FOR(i,k) scanf("%d",&a[i]);
              ~~~~~^~~~~~~~~~~~
cities.cpp:114:11: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
      scanf("%d %d %d",&x,&y,&w);
      ~~~~~^~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 22 / 22
• Subtask 2: 14 / 14
• Subtask 3: 15 / 15
• Subtask 4: 23 / 23
• Subtask 5: 26 / 26