Submission #61399

#	Time	Username	Problem	Language	Result	Execution time	Memory
61399		kingpig9	Duathlon (APIO18_duathlon)	C++11	0 / 100	165 ms	23160 KiB

count_triplets

#include <bits/stdc++.h>

using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
const int MAXN = 1e5 + 10;

#define debug(...) fprintf(stderr, __VA_ARGS__)
#define fi first
#define se second
#define all(v) (v).begin(), (v).end()
#define fillchar(a, s) memset((a), (s), sizeof(a))

ll sqr (ll x) {
	return x * x;
}

int N, M;
vector<int> adj[MAXN];
int sub[MAXN];

void dfs (int x, int p) {
	sub[x] = 1;
	if (p) {
		adj[x].erase(find(all(adj[x]), p));
	}

	for (int y : adj[x]) {
		dfs(y, x);
		sub[x] += sub[y];
	}
}

int main() {
	//subtask 5
	scanf("%d %d", &N, &M);
	assert(M == N - 1);
	for (int i = 1; i < N; i++) {
		int x, y;
		scanf("%d %d", &x, &y);
		adj[x].push_back(y);
		adj[y].push_back(x);
	}
	dfs(1, 0);

	ll ans = 0;
	for (int c = 1; c <= N; c++) {
		ans += sqr(N - 1) - sqr(N - sub[c]);
		for (int y : adj[c]) {
			ans -= sqr(sub[y]);
		}
	}
	printf("%lld\n", ans);
}

Compilation message (stderr)

count_triplets.cpp: In function 'int main()':
count_triplets.cpp:37:7: 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:41:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d %d", &x, &y);
   ~~~~~^~~~~~~~~~~~~~~~~

• 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