Submission #1150918

#	Time	Username	Problem	Language	Result	Execution time	Memory
1150918		dashka	Group Photo (JOI21_ho_t3)	C++20	100 / 100	262 ms	98312 KiB

Main

#include <cstdio>
#include <vector>
using namespace std;

const int INF = 1'000'000'007;

bool chmin(int &a, int b) {
	if (b < a) {
		a = b;
		return true;
	}
	return false;
}

int main() {
	int N;
	scanf("%d", &N);
	int H[N];
	for (int i = 0; i < N; i++) {
		scanf("%d", H + i);
		H[i]--;
	}
	int invH[N];
	for (int i = 0; i < N; i++) invH[H[i]] = i;

	int cntup[N][N + 1];  //cntup[pos][num] = count #(position > pos && number >= num)
	fill(cntup[N - 1], cntup[N], 0);
	for (int j = N - 1; j; j--) {
		for (int i = 0; i <= H[j]; i++) cntup[j - 1][i] = cntup[j][i] + 1;
		for (int i = H[j] + 1; i <= N; i++) cntup[j - 1][i] = cntup[j][i];
	}

	int dp[N + 1];
	dp[0] = 0;
	for (int i = 1; i <= N; i++) {
		dp[i] = INF;
		int tmp = 0;
		for (int j = i - 1; j >= 0; j--) {
			tmp += (N - i) + cntup[invH[j]][j] - 2 * cntup[invH[j]][i];
			chmin(dp[i], dp[j] + tmp);
		}
	}
	printf("%d\n", dp[N]);
	return 0;
}

Compilation message (stderr)

Main.cpp: In function 'int main()':
Main.cpp:17:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   17 |         scanf("%d", &N);
      |         ~~~~~^~~~~~~~~~
Main.cpp:20:22: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   20 |                 scanf("%d", H + i);
      |                 ~~~~~^~~~~~~~~~~~~

• Subtask 1: 5 / 5
• Subtask 2: 7 / 7
• Subtask 3: 32 / 32
• Subtask 4: 20 / 20
• Subtask 5: 36 / 36