GESP模板

堆最佳化的 dijkstra

#include<bits/stdc++.h>
using namespace std;
#define N 100005
#define M N<<2

int head[N],Next[M],ver[M],edge[M];
int tot;
int dist[M];
bool vis[M];
priority_queue<pair<int,int>>Q;

void ADD(int x,int y,int z) {
	ver[++tot] = y;
	edge[tot] = z;
	Next[tot] = head[x];
	head[x] = tot;
}

void dijkstra(int s){
	memset(dist,0x3f,sizeof(dist));
	memset(vis,0,sizeof(vis));
	dist[s] = 0;
	Q.push(make_pair(0,s));
	while(!Q.empty()){
		int x = Q.top().second;
		Q.pop();
		if(vis[x]) continue;
		vis[x] = 1;
		for(int i = head[x];~i;i = Next[i]){
			int y = ver[i];
			if(dist[y]>dist[x]+edge[i]){
				dist[y] = dist[x]+edge[i];
				Q.push(make_pair(-dist[y],y));
			}
		}
	}
}

int main() {
	int n,m,s;
	memset(head,-1,sizeof(head));
	tot = -1;
	cin>>n>>m>>s;
	for(int i = 1;i<=m;i++){
		int x,y,z;
		cin>>x>>y>>z;
		ADD(x,y,z);
	}
	dijkstra(s);
	for(int i = 1;i<=n;i++){
		cout<<dist[i]<<" ";
	}
	return 0;
}

求組合數

#include<bits/stdc++.h>
using namespace std;
#define int long long
#define N 100005
#define p 998244353
int fac[N];
int KSM(int a,int b){
	int res = 1;
	a%=p;
	for(;b;b>>=1,a = a*a%p)if(b&1) res = res*a%p;
	return res;
}
int inv(int x){
	return KSM(x,p-2);
}

int C(int n,int m){
	return ((fac[n]*inv(fac[m]))%p*inv(fac[n-m]))%p;
}

signed main(){
	fac[0] = 1;
	for(int i = 1;i<=N-5;i++){
		fac[i] = fac[i-1]*i;
	}
	while(1){
		int n,m;
		cin>>n>>m;
		cout<<C(n,m)<<endl;
	}
	return 0;
} 

最小生成樹

#include<bits/stdc++.h>
using namespace std;
#define N 100005
#define M N<<1
#define INF 0x3f3f3f3f
int F[N],n,m,sum,num;
struct E{
	int x,y,z;
}edge[M];

void init(int n){
	for(int i = 1;i<=n;i++){
		F[i] = i;
	}
}

bool cmp(E a, E b){
	return a.z<b.z;
}

int Find(int x){
	if(x == F[x]) return x;
	return F[x] = Find(F[x]);
}

int kruskal(){
	sort(edge+1,edge+m+1,cmp);
	init(n);
	for(int i = 1;i<=m;i++){
		int x = Find(edge[i].x);
		int y = Find(edge[i].y);
		if(x == y) continue;
		F[x] = y;
		num++;
		sum+=edge[i].z;
	}
	if(num == n-1) return sum;
	else return INF;
}

int main(){
	cin>>n>>m;
	for(int i = 1;i<=m;i++){
		cin>>edge[i].x>>edge[i].y>>edge[i].z;
	}
	int ans = kruskal();
	if(ans == INF){
		puts("orz");
	}
	else{
		cout<<ans;
	}
	return 0;
}