Submission #707730

#	Time	Username	Problem	Language	Result	Execution time	Memory
707730		rainboy	Olympic Bus (JOI20_ho_t4)	C11	100 / 100	292 ms	3260 KiB

ho_t4

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define N	200
#define M	50000
#define INF	0x3f3f3f3f

int min(int a, int b) { return a < b ? a : b; }

int ii[M], jj[M], ww[M], cc[M];
int *eh[N], eo[N], *fh[N], fo[N];

void append(int **eh, int *eo, int i, int h) {
	int o = eo[i]++;

	if (o >= 2 && (o & o - 1) == 0)
		eh[i] = (int *) realloc(eh[i], o * 2 * sizeof *eh[i]);
	eh[i][o] = h;
}

char visited[N]; int ff[N];

void dijkstra(int **eh, int *eo, int *dd, int n, int s, int h_) {
	int i, i_, o;

	memset(visited, 0, n * sizeof *visited);
	memset(dd, 0x3f, n * sizeof *dd), memset(ff, -1, n * sizeof *ff), dd[s] = 0;
	while (1) {
		i_ = -1;
		for (i = 0; i < n; i++)
			if (!visited[i] && dd[i] != INF && (i_ == -1 || dd[i_] > dd[i]))
				i_ = i;
		if (i_ == -1)
			break;
		i = i_;
		visited[i] = 1;
		for (o = eo[i]; o--; ) {
			int h = eh[i][o], j = i ^ ii[h] ^ jj[h], d = dd[i] + ww[h];

			if (h == h_)
				continue;
			if (dd[j] > d)
				dd[j] = d, ff[j] = h;
		}
	}
}

int main() {
	static int ddso[N], ddto[N], ddsi[N], ddti[N], ddso_[N], ddto_[N], ddsi_[N], ddti_[N];
	static char usedso[M], usedto[M], usedsi[M], usedti[M];
	int n, m, h, i, j, dst, dts, ans;

	scanf("%d%d", &n, &m);
	for (i = 0; i < n; i++) {
		eh[i] = (int *) malloc(2 * sizeof *eh[i]);
		fh[i] = (int *) malloc(2 * sizeof *fh[i]);
	}
	for (h = 0; h < m; h++) {
		scanf("%d%d%d%d", &ii[h], &jj[h], &ww[h], &cc[h]), ii[h]--, jj[h]--;
		append(eh, eo, ii[h], h), append(fh, fo, jj[h], h);
	}
	dijkstra(eh, eo, ddso, n, 0, -1);
	for (i = 0; i < n; i++)
		if (ff[i] != -1)
			usedso[ff[i]] = 1;
	dijkstra(eh, eo, ddto, n, n - 1, -1);
	for (i = 0; i < n; i++)
		if (ff[i] != -1)
			usedto[ff[i]] = 1;
	dijkstra(fh, fo, ddsi, n, 0, -1);
	for (i = 0; i < n; i++)
		if (ff[i] != -1)
			usedsi[ff[i]] = 1;
	dijkstra(fh, fo, ddti, n, n - 1, -1);
	for (i = 0; i < n; i++)
		if (ff[i] != -1)
			usedti[ff[i]] = 1;
	ans = INF;
	if (ddso[n - 1] != INF && ddto[0] != INF)
		ans = min(ans, ddso[n - 1] + ddto[0]);
	for (h = 0; h < m; h++) {
		if (usedso[h])
			dijkstra(eh, eo, ddso_, n, 0, h);
		else
			memcpy(ddso_, ddso, n * sizeof *ddso);
		if (usedto[h])
			dijkstra(eh, eo, ddto_, n, n - 1, h);
		else
			memcpy(ddto_, ddto, n * sizeof *ddto);
		if (usedsi[h])
			dijkstra(fh, fo, ddsi_, n, 0, h);
		else
			memcpy(ddsi_, ddsi, n * sizeof *ddsi);
		if (usedti[h])
			dijkstra(fh, fo, ddti_, n, n - 1, h);
		else
			memcpy(ddti_, ddti, n * sizeof *ddti);
		i = ii[h], j = jj[h];
		dst = ddso_[n - 1];
		if (ddso_[j] != INF && ddti_[i] != INF)
			dst = min(dst, ddso_[j] + ww[h] + ddti_[i]);
		dts = ddto_[0];
		if (ddto_[j] != INF && ddsi_[i] != INF)
			dts = min(dts, ddto_[j] + ww[h] + ddsi_[i]);
		if (dst != INF && dts != INF)
			ans = min(ans, dst + dts + cc[h]);
	}
	if (ans == INF)
		ans = -1;
	printf("%d\n", ans);
	return 0;
}

Compilation message (stderr)

ho_t4.c: In function 'append':
ho_t4.c:17:23: warning: suggest parentheses around '-' in operand of '&' [-Wparentheses]
   17 |  if (o >= 2 && (o & o - 1) == 0)
      |                     ~~^~~
ho_t4.c: In function 'main':
ho_t4.c:54:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   54 |  scanf("%d%d", &n, &m);
      |  ^~~~~~~~~~~~~~~~~~~~~
ho_t4.c:60:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   60 |   scanf("%d%d%d%d", &ii[h], &jj[h], &ww[h], &cc[h]), ii[h]--, jj[h]--;
      |   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 5 / 5
• Subtask 2: 11 / 11
• Subtask 3: 21 / 21
• Subtask 4: 63 / 63