Submission #1324688

#TimeUsernameProblemLanguageResultExecution timeMemory
1324688brendonwRainforest Jumps (APIO21_jumps)C++20
8 / 100
4065 ms5084 KiB
#include <bits/stdc++.h>

using namespace std;
const int MAXN = 2e5;
int h[MAXN], prevmx[MAXN], nxtmx[MAXN], idx[MAXN];
int n;
void init(int N, vector<int> H) {
	n = N;
	copy(H.begin(), H.end(), h);
	for (int i = 0; i < n; ++i) {
		idx[--h[i]] = i;
	}
	for (int i = 0; i < n; ++i) {
		prevmx[i] = i - 1;
		while (prevmx[i] != -1 && h[prevmx[i]] <= h[i]) {
			prevmx[i] = prevmx[prevmx[i]];
		}
	}
	for (int i = n - 1; i >= 0; --i) {
		nxtmx[i] = i + 1;
		while (nxtmx[i] < n && h[nxtmx[i]] <= h[i]) {
			nxtmx[i] = nxtmx[nxtmx[i]];
		}
	}
}

int minimum_jumps(int A, int B, int C, int D) {
	int mncnt = n;
	for (int i = B; i >= A; --i) {
		for (int j = C; j <= D; ++j) {
			if (prevmx[j] < i) {
				assert(h[i] < h[j]);
				vector<int> dp(n, n);
				dp[j] = 0;
				for (int k = h[j] - 1; k >= h[i]; --k) {
					int cur = idx[k];
					if (prevmx[cur] != -1) {
						dp[cur] = min(dp[cur], 1 + dp[prevmx[cur]]);
					}
					if (nxtmx[cur] != -1) {
						dp[cur] = min(dp[cur], 1 + dp[nxtmx[cur]]);
					}
				}
				mncnt = min(mncnt, dp[i]);
			}
		}
	}
	return mncnt == n ? -1 : mncnt;
}

//int main() {
//	init(7, {6, 1, 2, 3, 4, 5, 7});
//	cout << minimum_jumps(1, 1, 6, 6) << '\n';
////	cout << minimum_jumps(1, 3, 5, 6) << '\n';
////	cout << minimum_jumps(0, 1, 2, 2) << '\n';
////	return 0;
//}
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