Submission #484587

#	Time	Username	Problem	Language	Result	Execution time	Memory
484587		rainboy	Index (COCI21_index)	C11	110 / 110	2005 ms	51496 KiB

index

#include <stdio.h>

#define N	200000
#define LN	18	/* LN = ceil(log2(N)) */
#define N_	(1 + N * (LN + 1))

unsigned int X = 12345;

int rand_() {
	return (X *= 3) >> 1;
}

int aa[N];

void sort(int *ii, int l, int r) {
	while (l < r) {
		int i = l, j = l, k = r, i_ = ii[l + rand_() % (r - l)], tmp;

		while (j < k) {
			int c = aa[ii[j]] - aa[i_];

			if (c == 0)
				j++;
			else if (c < 0) {
				tmp = ii[i], ii[i] = ii[j], ii[j] = tmp;
				i++, j++;
			} else {
				k--;
				tmp = ii[j], ii[j] = ii[k], ii[k] = tmp;
			}
		}
		sort(ii, l, i);
		l = k;
	}
}

int ll[N_], rr[N_], kk[N_], _;

int update(int t, int l, int r, int i) {
	int t_ = ++_;

	kk[t_] = kk[t] + 1;
	if (r - l > 1) {
		int m = (l + r) / 2;

		if (i < m)
			ll[t_] = update(ll[t], l, m, i), rr[t_] = rr[t];
		else
			ll[t_] = ll[t], rr[t_] = update(rr[t], m, r, i);
	}
	return t_;
}

int query(int t, int l, int r, int ql, int qr) {
	int m;

	if (qr <= l || r <= ql || t == 0)
		return 0;
	if (ql <= l && r <= qr)
		return kk[t];
	m = (l + r) / 2;
	return query(ll[t], l, m, ql, qr) + query(rr[t], m, r, ql, qr);
}

int main() {
	static int ii[N], tt[N + 1];
	int n, q, i, a, t;

	scanf("%d%d", &n, &q);
	for (i = 0; i < n; i++) {
		scanf("%d", &aa[i]);
		ii[i] = i;
	}
	sort(ii, 0, n);
	for (a = n, i = n - 1, t = 0; a >= 0; a--) {
		while (i >= 0 && aa[ii[i]] >= a)
			t = update(t, 0, n, ii[i--]);
		tt[a] = t;
	}
	while (q--) {
		int l, r, lower, upper;

		scanf("%d%d", &l, &r), l--;
		lower = 1, upper = r - l + 1;
		while (upper - lower > 1) {
			int a = (lower + upper) / 2;

			if (query(tt[a], 0, n, l, r) >= a)
				lower = a;
			else
				upper = a;
		}
		printf("%d\n", lower);
	}
	return 0;
}

Compilation message (stderr)

index.c: In function 'main':
index.c:69:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   69 |  scanf("%d%d", &n, &q);
      |  ^~~~~~~~~~~~~~~~~~~~~
index.c:71:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   71 |   scanf("%d", &aa[i]);
      |   ^~~~~~~~~~~~~~~~~~~
index.c:83:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   83 |   scanf("%d%d", &l, &r), l--;
      |   ^~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 20 / 20
• Subtask 2: 40 / 40
• Subtask 3: 50 / 50