제출 #405118

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
405118		rainboy	Shortcut (IOI16_shortcut)	C11	71 / 100	2089 ms	2252 KiB

shortcut

#include "shortcut_c.h"

#define N	1000000
#define INF	0x3f3f3f3f3f3f3f3f

long long min(long long a, long long b) { return a < b ? a : b; }
long long max(long long a, long long b) { return a > b ? a : b; }

unsigned int X = 12345;

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

long long *aa;

#include <stdio.h>

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)
			if (aa[ii[j]] == aa[i_])
				j++;
			else if (aa[ii[j]] < aa[i_]) {
				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;
	}
}

long long find_shortcut(int n, int *xx_, int *dd, int c) {
	static long long xx[N], yy[N], zz[N];
	static int kk[N], ll[N];
	int i, j, j1, j2, k, l, d, d1, d2, can;
	long long x, y_, z_, lower, upper;

	for (i = 1; i < n; i++)
		xx[i] = xx[i - 1] + xx_[i - 1];
	d1 = d2 = 0;
	for (i = 0; i < n; i++) {
		d = dd[i], x = xx[i], yy[i] = d - x, zz[i] = d + x;
		if (d1 < d)
			d2 = d1, d1 = d;
		else if (d2 < d)
			d2 = d;
		kk[i] = ll[i] = i;
	}
	aa = yy, sort(kk, 0, n);
	aa = zz, sort(ll, 0, n);
	lower = d1 + d2 - 1, upper = xx[n - 1] + d1 + d2;
	while (upper - lower > 1) {
		long long d = (lower + upper) / 2, p, q, r, s;

		p = q = r = s = INF, y_ = -INF, z_ = zz[ll[n - 1]];
		for (k = 0; k < n; k++)
			for (l = k + 1; l < n; l++)
				if (yy[k] + zz[l] > d) {
					/* dd[k] + dd[l] + |xx[k] - xx[i]| + c + |xx[l] - xx[j]| <= d
					 *
					 * max(xx[k] - xx[i], xx[i] - xx[k]) + max(xx[l] - xx[j], xx[j] - xx[l])
					 * <= d - (dd[k] + dd[l] + c)
					 *
					 * xx[k] - xx[i] + xx[l] - xx[j] <= d - (dd[k] + dd[l] + c)
					 * xx[k] - xx[i] + xx[j] - xx[l] <= d - (dd[k] + dd[l] + c)
					 * xx[i] - xx[k] + xx[l] - xx[j] <= d - (dd[k] + dd[l] + c)
					 * xx[i] - xx[k] + xx[j] - xx[l] <= d - (dd[k] + dd[l] + c)
					 *
					 * - xx[i] - xx[j] <= d - (dd[k] + dd[l] + c + xx[k] + xx[l])
					 * - xx[i] + xx[j] <= d - (dd[k] + dd[l] + c + xx[k] - xx[l])
					 * + xx[i] - xx[j] <= d - (dd[k] + dd[l] + c - xx[k] + xx[l])
					 * + xx[i] + xx[j] <= d - (dd[k] + dd[l] + c - xx[k] - xx[l]) */
					p = min(p, d - (zz[k] + zz[l] + c));
					q = min(q, d - (zz[k] + yy[l] + c));
					r = min(r, d - (yy[k] + zz[l] + c));
					s = min(s, d - (yy[k] + yy[l] + c));
				}
		can = 0;
		for (i = 0, j1 = -1, j2 = n - 1; i < n; i++) {
			x = xx[i];
			while (j1 + 1 < n && - x + xx[j1 + 1] <= q)
				j1++;
			while (j2 >= 0 && + x + xx[j2] > s)
				j2--;
			j = min(j1, j2);
			if (i < j && - x - xx[j] <= p && + x - xx[j] <= r) {
				can = 1;
				break;
			}
		}
		if (can)
			upper = d;
		else
			lower = d;
	}
	return upper;
}

컴파일 시 표준 에러 (stderr) 메시지

shortcut.c: In function 'find_shortcut':
shortcut.c:42:19: warning: variable 'z_' set but not used [-Wunused-but-set-variable]
   42 |  long long x, y_, z_, lower, upper;
      |                   ^~
shortcut.c:42:15: warning: variable 'y_' set but not used [-Wunused-but-set-variable]
   42 |  long long x, y_, z_, lower, upper;
      |               ^~

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• Subtask 3: 8 / 8
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