Submission #112272

#	Time	Username	Problem	Language	Result	Execution time	Memory
112272		figter001	Duathlon (APIO18_duathlon)	C++17	0 / 100	216 ms	12252 KiB

count_triplets

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;
const int nax = 2e5;

vector<int> g[nax];
int seg[4*nax],lazy[4*nax],fr[nax],to[nax],id[nax];
int T,n,m;
ll ans;

void pro(int n,int s,int e){
	seg[n] += lazy[n];
	if(s != e){
		lazy[n*2] += lazy[n];
		lazy[n*2+1] += lazy[n];
	}
	lazy[n] = 0;
}

void update(int n,int s,int e,int l,int r,int val){
	pro(n,s,e);
	if(s > r || e < l)
		return;
	if(s >= l && e <= r){
		lazy[n] += val;
		pro(n,s,e);
		return;
	}
	update(n*2,s,(s+e)/2,l,r,val);
	update(n*2+1,(s+e)/2+1,e,l,r,val);
	seg[n] = seg[n*2] + seg[n*2+1];
}

ll get(int n,int s,int e,int l,int r){
	pro(n,s,e);
	if(s > r || e < l)
		return 0;
	if(s >= l && e <= r)
		return seg[n];
	return get(n*2,s,(s+e)/2,l,r) + get(n*2+1,(s+e)/2+1,e,l,r);
}

void dfs(int u,int p,int d){
	id[u] = fr[u] = ++T;

	update(1,1,n,T,T,d);

	for(int v : g[u]){
		if(v == p)
			continue;
		dfs(v,u,d+1);
	}

	to[u] = T;
}

void calc(int u,int p){
	ans += get(1,1,n,1,n) - n + 1;
	for(int v : g[u]){
		if(v == p)
			continue;
		update(1,1,n,1,n,1);
		update(1,1,n,fr[v],to[v],-2);
		calc(v,u);

		update(1,1,n,1,n,-1);
		update(1,1,n,fr[v],to[v],2);
	}

}

int main(){
	scanf("%d%d",&n,&m);
	for(int i=0;i<m;i++){
		int u,v;
		scanf("%d%d",&u,&v);
		g[u].push_back(v);
		g[v].push_back(u);
	}
	if(n == m){
		ans = n * (n-1) * (n-2);
	}else if(n == m+1){
		dfs(1,0,0);
		calc(1,0);
	}else assert(0);

	printf("%lld\n", ans);
}

Compilation message (stderr)

count_triplets.cpp: In function 'int main()':
count_triplets.cpp:77:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d",&n,&m);
  ~~~~~^~~~~~~~~~~~~~
count_triplets.cpp:80:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d",&u,&v);
   ~~~~~^~~~~~~~~~~~~~

• Subtask 1: 0 / 5
• Subtask 2: 0 / 11
• Subtask 3: 0 / 8
• Subtask 4: 0 / 10
• Subtask 5: 0 / 13
• Subtask 6: 0 / 15
• Subtask 7: 0 / 20
• Subtask 8: 0 / 8
• Subtask 9: 0 / 10