#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define N 100000
#define INF 0x3f3f3f3f3f3f3f3fLL
long long abs_(long long a) { return a > 0 ? a : -a; }
unsigned int X = 12345;
int rand_() {
return (X *= 3) >> 1;
}
int *ej[N], *ew[N], eo[N];
void append(int i, int j, int w) {
int o = eo[i]++;
if (o >= 2 && (o & o - 1) == 0) {
ej[i] = (int *) realloc(ej[i], o * 2 * sizeof *ej[i]);
ew[i] = (int *) realloc(ew[i], o * 2 * sizeof *ew[i]);
}
ej[i][o] = j, ew[i][o] = w;
}
long long *dd; int iq[N + 1], pq[N], cnt;
int lt(int i, int j) { return dd[i] < dd[j]; }
int p2(int p) {
return (p *= 2) > cnt ? 0 : (p < cnt && lt(iq[p + 1], iq[p]) ? p + 1 : p);
}
void pq_up(int i) {
int p, q, j;
for (p = pq[i]; (q = p / 2) && lt(i, j = iq[q]); p = q)
iq[pq[j] = p] = j;
iq[pq[i] = p] = i;
}
void pq_dn(int i) {
int p, q, j;
for (p = pq[i]; (q = p2(p)) && lt(j = iq[q], i); p = q)
iq[pq[j] = p] = j;
iq[pq[i] = p] = i;
}
void pq_add_last(int i) {
iq[pq[i] = ++cnt] = i;
}
int pq_remove_first() {
int i = iq[1], j = iq[cnt--];
if (j != i)
pq[j] = 1, pq_dn(j);
pq[i] = 0;
return i;
}
void dijkstra(int n, int s) {
int i, o;
memset(dd, 0x3f, n * sizeof *dd);
dd[s] = 0, pq_add_last(s);
while (cnt) {
i = pq_remove_first();
for (o = eo[i]; o--; ) {
int j = ej[i][o], w = ew[i][o];
long long d = dd[i] + w;
if (dd[j] > d) {
if (dd[j] == INF)
pq_add_last(j);
dd[j] = d, pq_up(j);
}
}
}
}
void sort(long long *aa, int l, int r) {
while (l < r) {
int i = l, j = l, k = r;
long long a = aa[l + rand_() % (r - l)], tmp;
while (j < k)
if (aa[j] == a)
j++;
else if (aa[j] < a) {
tmp = aa[i], aa[i] = aa[j], aa[j] = tmp;
i++, j++;
} else {
k--;
tmp = aa[j], aa[j] = aa[k], aa[k] = tmp;
}
sort(aa, l, i);
l = k;
}
}
int main() {
int t;
scanf("%d", &t);
while (t--) {
static long long dd0[N], dd1[N], xx[N], yy[N];
int n, m, h, i, j, w;
long long x, y, sum;
scanf("%d%d", &n, &m);
for (i = 0; i < n; i++) {
ej[i] = (int *) malloc(2 * sizeof *ej[i]);
ew[i] = (int *) malloc(2 * sizeof *ew[i]);
eo[i] = 0;
}
for (h = 0; h < m; h++) {
scanf("%d%d%d", &i, &j, &w), i--, j--;
append(i, j, w), append(j, i, w);
}
dd = dd0, dijkstra(n, 0);
dd = dd1, dijkstra(n, 1);
for (i = 0; i < n; i++) {
xx[i] = dd0[i] + dd1[i];
yy[i] = dd0[i] - dd1[i];
}
sum = 0;
sort(xx, 0, n);
x = xx[n / 2];
for (i = 0; i < n; i++)
sum += abs_(xx[i] - x);
sort(yy, 0, n);
y = yy[n / 2];
for (i = 0; i < n; i++)
sum += abs_(yy[i] - y);
printf("%.12f\n", (double) sum / 2 / n);
for (i = 0; i < n; i++)
free(ej[i]), free(ew[i]);
}
return 0;
}
Compilation message
F.c: In function 'append':
F.c:21:23: warning: suggest parentheses around '-' in operand of '&' [-Wparentheses]
21 | if (o >= 2 && (o & o - 1) == 0) {
| ~~^~~
F.c: In function 'main':
F.c:108:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
108 | scanf("%d", &t);
| ^~~~~~~~~~~~~~~
F.c:114:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
114 | scanf("%d%d", &n, &m);
| ^~~~~~~~~~~~~~~~~~~~~
F.c:121:4: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
121 | scanf("%d%d%d", &i, &j, &w), i--, j--;
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1 ms |
4440 KB |
Output is correct |
| 2 |
Correct |
25 ms |
5136 KB |
Output is correct |
| 3 |
Correct |
866 ms |
47924 KB |
Output is correct |
