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
54
55
56
57
58
59
60
61
62
63
64
65
66
67
|
// 1964. Find the Longest Valid Obstacle Course at Each Position
#include "leetcode.h"
/*
* you want to build obstacle courses. you are given a 0-indexed integer array
* 'obstacles' of length 'n' where 'obstacles[i]' describes the height of the
* i'th obstacle. for every index 'i' between 0 and 'n - 1' (inclusive), find
* the length of the longest obstacle course in 'obstacles' such that:
* - you choose any number of obstacles between 0 and 'i' inclusive
* - you must include the i'th obstacle in the course
* - you must put the chosen obstacles in the same order as they appear in
* 'obstacles'
* - every obstacle (except the first) is taller than or the same height as the
* obstacle immediately before it return an array 'ans' of length 'n', where
* 'ans[i]' is the length of the longest obstacle course for index 'i' as
* described above
*/
int find(int *arr, int start, int end, int target) {
while (start < end) {
int mid = start + (end - start) / 2;
if (arr[mid] == target)
start = mid + 1;
else if (arr[mid] > target)
end = mid;
else
start = mid + 1;
}
return start;
}
int *longestObstacleCourseAtEachPosition(int *obstacles, int obstaclesSize,
int *returnSize) {
int *ans = (int *)calloc(obstaclesSize, sizeof(int));
int *cnt = (int *)calloc(obstaclesSize, sizeof(int)), n = 1;
ans[0] = 1;
cnt[0] = obstacles[0];
for (int i = 1; i < obstaclesSize; i++) {
int idx = find(cnt, 0, n, obstacles[i]);
if (idx == n)
cnt[n++] = obstacles[i];
else
cnt[idx] = obstacles[i];
ans[i] = idx + 1;
}
*returnSize = obstaclesSize;
free(cnt);
return ans;
}
int main() {
int o1[] = {1, 2, 3, 2}, o2[] = {2, 2, 1}, o3[] = {3, 1, 5, 6, 4, 2}, rs1,
rs2, rs3;
int *locaep1 = longestObstacleCourseAtEachPosition(o1, ARRAY_SIZE(o1), &rs1);
int *locaep2 = longestObstacleCourseAtEachPosition(o2, ARRAY_SIZE(o2), &rs2);
int *locaep3 = longestObstacleCourseAtEachPosition(o3, ARRAY_SIZE(o3), &rs3);
for (int i = 0; i < rs1; i++)
printf("%d ", locaep1[i]); // expect: 1 2 3 3
printf("\n");
for (int i = 0; i < rs2; i++)
printf("%d ", locaep2[i]); // expect: 1 2 1
printf("\n");
for (int i = 0; i < rs3; i++)
printf("%d ", locaep3[i]); // expect: 1 1 2 3 2 2
printf("\n");
free(locaep1), free(locaep2), free(locaep3);
}
|