Submission #105768

#	Time	Username	Problem	Language	Result	Execution time	Memory
105768		Pro_ktmr	Fireworks (APIO16_fireworks)	C++14	0 / 100	16 ms	14464 KiB

fireworks

#include"bits/stdc++.h"
using namespace std;
#define LL long long
#define REP(i, n) for(int (i)=0; (i)<(n); (i)++)
#define PB push_back
#define MP make_pair
#define MOD 1000000007

int N, M;
vector<pair<int, LL>> edge[300001];
int par[300001];
vector<pair<int, LL>> chi[300001];
vector<pair<int, int>> node;
LL a[300001] ={}, b[300001] ={};

void dfs(int now, int p){
	for(int i=0; i<edge[now].size(); i++){
		if(edge[now][i].first == p) continue;
		chi[now].PB(MP(edge[now][i].first, edge[now][i].second));
		par[edge[now][i].first] = now;
		dfs(edge[now][i].first, now);
	}
}

int d[300001] ={};
int depth(int now){
	if(now == 0) return 0;
	if(d[now] != 0) return d[now];
	return d[now] = depth(par[now]) + 1;
}

LL my_binary_search(int now, LL ans, LL ok, LL ng){
	while(abs(ok-ng) > 1){
		LL m = (ok+ng) / 2;
		LL tmp = 0;
		for(int i=0; i<chi[now].size(); i++){
			if(a[chi[now][i].first] > m) tmp += a[chi[now][i].first] - m;
			else if(b[chi[now][i].first] < m) tmp += m - b[chi[now][i].first];
		}
		if(tmp == ans) ok = m;
		else ng = m;
	}
	return ok;
}

LL func(int now, LL tmp){
	LL ans = 0;
	for(int i=0; i<chi[now].size(); i++){
		if(a[chi[now][i].first] > tmp) ans += a[chi[now][i].first] - tmp;
		else if(b[chi[now][i].first] < tmp) ans += tmp - b[chi[now][i].first];
	}
	return ans;
}

LL sanbun(int now){
	/*LL l = 0;
	LL r = 1000000000LL*300000LL;
	//[l,r)
	while(r-l > 1){
		LL m = (l+r) / 2;
		if(func(now, m-1) <= func(now, m)) r = m;
		else l = m;
	}
	return l;*/
	int m = INT_MAX;
	int ans;
	for(int i=0; i<2000; i++){
		int tmp = func(now, i);
		if(m > tmp){
			m = tmp;
			ans = i;
		}
	}
	for(int i=0; i<2000; i++){
		int tmp = func(now, i);
		if(tmp == m) continue;
		if(tmp == func(now, i+1)){
			assert(false);
		}
	}
	return ans;
}

int main(){
	scanf("%d%d", &N, &M);
	for(int i=0; i<N+M-1; i++){
		int P;
		LL C;
		scanf("%d%lld", &P, &C);
		P--;
		edge[i+1].PB(MP(P, C));
		edge[P].PB(MP(i+1, C));
	}

	par[0] = -1;
	dfs(0, -1);

	for(int i=0; i<N+M; i++){
		node.PB(MP(depth(i), i));
	}
	sort(node.begin(), node.end());
	reverse(node.begin(), node.end());

	LL ans = 0;
	for(int i=0; i<N+M; i++){
		int now = node[i].second;
		if(chi[now].size() == 0){
			a[now] = 0;
			b[now] = 0;
			continue;
		}
		for(int j=0; j<chi[now].size(); j++){
			a[chi[now][j].first] += chi[now][j].second;
			b[chi[now][j].first] += chi[now][j].second;
		}

		LL tmp = sanbun(now);
		LL nowAns = 0;
		for(int j=0; j<chi[now].size(); j++){
			if(tmp < a[chi[now][j].first]) nowAns += a[chi[now][j].first] - tmp;
			else if(tmp > b[chi[now][j].first]) nowAns += tmp - b[chi[now][j].first];
		}
		ans += nowAns;
		a[now] = my_binary_search(now, nowAns, tmp, -1);
		b[now] = my_binary_search(now, nowAns, tmp, 1000000000LL*300000LL);
		//cout << nowAns << " " << a[now] << " " << b[now] << endl;
	}

	cout << ans << endl;
}

Compilation message (stderr)

fireworks.cpp: In function 'void dfs(int, int)':
fireworks.cpp:17:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0; i<edge[now].size(); i++){
               ~^~~~~~~~~~~~~~~~~
fireworks.cpp: In function 'long long int my_binary_search(int, long long int, long long int, long long int)':
fireworks.cpp:36:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i=0; i<chi[now].size(); i++){
                ~^~~~~~~~~~~~~~~~
fireworks.cpp: In function 'long long int func(int, long long int)':
fireworks.cpp:48:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0; i<chi[now].size(); i++){
               ~^~~~~~~~~~~~~~~~
fireworks.cpp: In function 'int main()':
fireworks.cpp:112:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int j=0; j<chi[now].size(); j++){
                ~^~~~~~~~~~~~~~~~
fireworks.cpp:119:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int j=0; j<chi[now].size(); j++){
                ~^~~~~~~~~~~~~~~~
fireworks.cpp:85:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d", &N, &M);
  ~~~~~^~~~~~~~~~~~~~~~
fireworks.cpp:89:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%lld", &P, &C);
   ~~~~~^~~~~~~~~~~~~~~~~~
fireworks.cpp: In function 'long long int sanbun(int)':
fireworks.cpp:81:9: warning: 'ans' may be used uninitialized in this function [-Wmaybe-uninitialized]
  return ans;
         ^~~

• Subtask 1: 0 / 7
• Subtask 2: 0 / 19
• Subtask 3: 0 / 29
• Subtask 4: 0 / 45