1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
|
// 452. Minimum Number of Arrows to Burst Balloons
#include "leetcode.h"
/*
* there are some spherical balloons taped onto a flat wall that represents the
* xy plane. the ballooons are represented as a 2d integer array 'points' where
* 'points[i] = [x_start, x_end]'. you do not know the exact y coordinates of
* the balloons. arrows can be shot up directly vertically in the positive y
* direction. from different points along the x axis. given the array points,
* return the minimum number of arrows that must be shot to burst all balloons.
*/
int cmp(const void **p1, const void **p2) {
int *arr1 = *(int **)p1;
int *arr2 = *(int **)p2;
if (arr1[1] == arr2[1]) {
if (arr1[0] == arr2[0])
return 0;
else if (arr1[0] > arr2[0])
return 1;
else
return -1;
} else {
if (arr1[1] == arr2[1])
return 0;
else if (arr1[1] > arr2[1])
return 1;
else
return -1;
}
}
int findMinArrowShots(int **points, int pointsSize, int *pointsColSize) {
qsort(points, pointsSize, sizeof(int *), cmp);
int k = points[0][1], cnt = 1;
for (int i = 1; i < pointsSize; i++) {
if (points[i][0] > k) {
cnt++;
k = points[i][1];
}
}
return cnt;
}
int main() {
int p1[4][2] = {{10, 16}, {2, 8}, {1, 6}, {7, 12}},
p2[4][4] = {{1, 2}, {3, 4}, {5, 6}, {7, 8}};
int pcs1, pcs2;
printf("%d\n",
findMinArrowShots((int **)p1, ARRAY_SIZE(p1), &pcs1)); // expect: 2
printf("%d\n",
findMinArrowShots((int **)p2, ARRAY_SIZE(p2), &pcs2)); // expect: 2
}
|