Submission #157684

#	Time	Username	Problem	Language	Result	Execution time	Memory
157684		imyujin	Sparklers (JOI17_sparklers)	C++17	100 / 100	124 ms	7028 KiB

sparklers

#include <bits/stdc++.h>
using namespace std;

typedef long long lint;
typedef pair<lint, lint> pll;

#define fi first
#define se second

const int MAXN = 100010;
const int INF = 1 << 30;

lint X[MAXN];

void solve(vector<lint> &v, vector<pll> &r, vector<pll> &x) {
	for(auto &a : v) {
		pll t = pll(a, max(-a, 0ll));
		while(!r.empty() && t.fi < 0) {
			t.se = max(t.se, r.back().se - t.fi);
			t.fi += r.back().fi;
			r.pop_back();
		}
		(t.fi >= 0 ? r : x).push_back(t);
	}
}

int main() {
	ios::sync_with_stdio(0); cin.tie(0);
	int N, K;
	lint T;

	cin >> N >> K >> T;
	for(int i = 1; i <= N; i++) cin >> X[i];

	lint s = 0, e = INF;
	while(s < e) {
		lint m = (s + e) / 2;
		vector<lint> v1, v2;
		for(int i = 1; i < K; i++) v1.push_back(2 * T * m - X[i + 1] + X[i]);
		for(int i = N; i > K; i--) v2.push_back(2 * T * m - X[i] + X[i - 1]);
		vector<pll> r1, r2, x1, x2;
		solve(v1, r1, x1);
		solve(v2, r2, x2);
		/*
		printf("m = %lld\nv1 : ", m);
		for(auto a : v1) printf("%lld ", a);
		printf("\nv2 : ");
		for(auto a : v2) printf("%lld ", a);
		printf("\nr1 : ");
		for(auto a : r1) printf("(%lld, %lld) ", a.fi, a.se);
		printf("\nr2 : ");
		for(auto a : r2) printf("(%lld, %lld) ", a.fi, a.se);
		printf("\n");
		*/
		lint t = 0;
		int p1 = int(r1.size()) - 1, p2 = int(r2.size()) - 1;
		while(p1 >= 0 || p2 >= 0) {
			if(p1 >= 0 && t >= r1[p1].se) t += r1[p1--].fi;
			else if(p2 >= 0 && t >= r2[p2].se) t += r2[p2--].fi;
			else break;
		}
		if(p1 >= 0 || p2 >= 0) {
			s = m + 1;
			continue;
		}
		p1 = p2 = 0;
		t = 0;
		for(auto a : v1) t += a;
		for(auto a : v2) t += a;
		while(p1 < x1.size() || p2 < x2.size()) {
			if(p1 < x1.size() && t - x1[p1].fi >= x1[p1].se) t -= x1[p1++].fi;
			else if(p2 < x2.size() && t - x2[p2].fi >= x2[p2].se) t -= x2[p2++].fi;
			else break;
		}
		if(p1 < x1.size() || p2 < x2.size()) s = m + 1;
		else e = m;
	}
	cout << s << "\n";
	return 0;
}

Compilation message (stderr)

sparklers.cpp: In function 'int main()':
sparklers.cpp:70:12: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   while(p1 < x1.size() || p2 < x2.size()) {
         ~~~^~~~~~~~~~~
sparklers.cpp:70:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   while(p1 < x1.size() || p2 < x2.size()) {
                           ~~~^~~~~~~~~~~
sparklers.cpp:71:10: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    if(p1 < x1.size() && t - x1[p1].fi >= x1[p1].se) t -= x1[p1++].fi;
       ~~~^~~~~~~~~~~
sparklers.cpp:72:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    else if(p2 < x2.size() && t - x2[p2].fi >= x2[p2].se) t -= x2[p2++].fi;
            ~~~^~~~~~~~~~~
sparklers.cpp:75:9: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   if(p1 < x1.size() || p2 < x2.size()) s = m + 1;
      ~~~^~~~~~~~~~~
sparklers.cpp:75:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   if(p1 < x1.size() || p2 < x2.size()) s = m + 1;
                        ~~~^~~~~~~~~~~

• Subtask 1: 30 / 30
• Subtask 2: 20 / 20
• Subtask 3: 50 / 50