Submission #145721

#	Time	Username	Problem	Language	Result	Execution time	Memory
145721		osaaateiasavtnl	Candies (JOI18_candies)	C++17	0 / 100	24 ms	376 KiB

candies

#include<bits/stdc++.h>
using namespace std;
#define int long long 
#define ii pair <int, int>
#define app push_back
#define all(a) a.begin(), a.end()
#define bp __builtin_popcount
const int N = 2e5 + 7, INF = 1e18 + 7;
int a[N];
bool used[N];
signed main() {
    #ifdef HOME
    //freopen("input.txt", "r", stdin);
    #else
    ios_base::sync_with_stdio(0); cin.tie(0);
    #endif
    int n; cin >> n; for (int i = 1; i <= n; ++i) cin >> a[i];
    int ans = 0;
   	for (int _ = 1; _ <= (n + 1) >> 1; ++_) {
   		int mx = -INF;
		for (int i = 1; i <= n; ++i) {
			if (!used[i] && !used[i - 1] && !used[i + 1]) mx = max(mx, a[i]);
		}
		vector <int> p;
		for (int i = 1; i <= n; ++i) {
			if (used[i]) p.app(i);
		}
		int l = 0;
		while (l < p.size()) {
			int r = l;
			while (r + 1 < p.size() && p[r + 1] == p[l] + 2) ++r;
			if (1 < p[l] && p[r] < n) {
				int sum = a[p[l] - 1] + a[p[r] + 1];
				for (int i = p[l] + 1; i < p[r]; i += 2) sum += a[i];
				for (int i = p[l]; i <= p[r]; i += 2) sum -= a[i];
				mx = max(mx, sum);
			}
			l = r + 1;
		}

		ans += mx;

		bool mem = 0;
		for (int i = 1; i <= n; ++i) {
			if (!used[i] && !used[i - 1] && !used[i + 1] && a[i] == mx) {
				used[i] = 1; mem = 1; break;
			}
		}
		if (!mem) {
		l = 0;
		while (l < p.size()) {
			int r = l;
			while (r + 1 < p.size() && p[r + 1] == p[l] + 2) ++r;
			if (1 < p[l] && p[r] < n) {
				int sum = a[p[l] - 1] + a[p[r] + 1];
				for (int i = p[l] + 1; i < p[r]; i += 2) sum += a[i];
				for (int i = p[l]; i <= p[r]; i += 2) sum -= a[i];
				if (sum == mx) {
					used[p[l] - 1] = used[p[r] + 1] = 1;
					for (int i = p[l] + 1; i < p[r]; i += 2) used[i] = 1;
					for (int i = p[l]; i <= p[r]; i += 2) used[i] = 0;
					break;
				}
			}
			l = r + 1;
		}		
		}

		cout << ans << '\n';
   	}
}

Compilation message (stderr)

candies.cpp: In function 'int main()':
candies.cpp:29:12: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   while (l < p.size()) {
          ~~^~~~~~~~~~
candies.cpp:31:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    while (r + 1 < p.size() && p[r + 1] == p[l] + 2) ++r;
           ~~~~~~^~~~~~~~~~
candies.cpp:51:12: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   while (l < p.size()) {
          ~~^~~~~~~~~~
candies.cpp:53:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    while (r + 1 < p.size() && p[r + 1] == p[l] + 2) ++r;
           ~~~~~~^~~~~~~~~~

• Subtask 1: 0 / 8
• Subtask 2: 0 / 92