carloscn
commented
11 months ago Analysis
#define MAX_NUM 50
int32_t distinct_difference_array(int32_t *nums, size_t nums_size)
{
int32_t ret = 0;
int32_t *rom = NULL;
UTILS_CHECK_PTR(nums);
UTILS_CHECK_LEN(nums_size);
rom = (int32_t *)calloc(nums_size, sizeof(size_t));
UTILS_CHECK_PTR(rom);
bool prefix[MAX_NUM + 1] = {0};
bool suffix[MAX_NUM + 1] = {0};
for (size_t i = 0; i < nums_size; i ++) {
suffix[nums[i]] = true;
}
for (size_t i = 0; i < nums_size; i ++) {
suffix[nums[i]] = false;
prefix[nums[i]] = true;
size_t prefix_count = 0, suffix_count = 0;
for (size_t j = 1; j <= MAX_NUM; j ++) {
prefix_count += prefix[j]?1:0;
suffix_count += suffix[j]?1:0;
}
rom[i] = prefix_count - suffix_count;
}
memcpy(nums, rom, sizeof(int32_t) * nums_size);
finish:
UTILS_SAFE_FREE(rom);
return ret;
}
Description
You are given a 0-indexed array nums of length n.
The distinct difference array of nums is an array diff of length n such that diff[i] is equal to the number of distinct elements in the suffix nums[i + 1, ..., n - 1] subtracted from the number of distinct elements in the prefix nums[0, ..., i].
Return the distinct difference array of nums.
Note that nums[i, ..., j] denotes the subarray of nums starting at index i and ending at index j inclusive. Particularly, if i > j then nums[i, ..., j] denotes an empty subarray.
Example 1:
Input: nums = [1,2,3,4,5] Output: [-3,-1,1,3,5] Explanation: For index i = 0, there is 1 element in the prefix and 4 distinct elements in the suffix. Thus, diff[0] = 1 - 4 = -3. For index i = 1, there are 2 distinct elements in the prefix and 3 distinct elements in the suffix. Thus, diff[1] = 2 - 3 = -1. For index i = 2, there are 3 distinct elements in the prefix and 2 distinct elements in the suffix. Thus, diff[2] = 3 - 2 = 1. For index i = 3, there are 4 distinct elements in the prefix and 1 distinct element in the suffix. Thus, diff[3] = 4 - 1 = 3. For index i = 4, there are 5 distinct elements in the prefix and no elements in the suffix. Thus, diff[4] = 5 - 0 = 5.
Example 2:
Input: nums = [3,2,3,4,2] Output: [-2,-1,0,2,3] Explanation: For index i = 0, there is 1 element in the prefix and 3 distinct elements in the suffix. Thus, diff[0] = 1 - 3 = -2. For index i = 1, there are 2 distinct elements in the prefix and 3 distinct elements in the suffix. Thus, diff[1] = 2 - 3 = -1. For index i = 2, there are 2 distinct elements in the prefix and 2 distinct elements in the suffix. Thus, diff[2] = 2 - 2 = 0. For index i = 3, there are 3 distinct elements in the prefix and 1 distinct element in the suffix. Thus, diff[3] = 3 - 1 = 2. For index i = 4, there are 3 distinct elements in the prefix and no elements in the suffix. Thus, diff[4] = 3 - 0 = 3.
Constraints:
1 <= n == nums.length <= 50 1 <= nums[i] <= 50