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// 2860. Happy Students
#include "leetcode.h"
/*
* you are given a 0 indexed integer array 'nums' of length 'n' where 'n' is the
* total number of students in the class. the class teacher tries to select a
* group of students so that all the students remain happy. the i'th student
* will become happy if one of these two conditions is met: the student is
* selected and the total number of selected students is strictly greater than
* 'nums[i]', or the student is not selected and the total number of selected
* students is strictly less than 'nums[i]'. return the number of ways to select
* a group of students os that everyone remains happy
*/
static int cmp(const int *const a, const int *const b) { return *a - *b; }
int countWays(int *nums, int numsSize) {
qsort(nums, numsSize, sizeof(int), &cmp);
int cnt = 0;
if (nums[0])
cnt++;
for (int i = 1; i < numsSize; i++)
if (nums[i - 1] < i && nums[i] > i)
cnt++;
if (nums[numsSize - 1] < numsSize)
cnt++;
return cnt;
}
int main() {
int n1[] = {1, 1}, n2[] = {6, 0, 3, 3, 6, 7, 2, 7};
printf("%d\n", countWays(n1, ARRAY_SIZE(n1))); // expect: 2
printf("%d\n", countWays(n2, ARRAY_SIZE(n2))); // expect: 3
}
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