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// 2044. Count Number of Maximum Bitwise-OR Subsets
#include "leetcode.h"
/*
* given an integer array 'nums', find the maximum possible bitwise OR of a
* subset of 'nums' and return the number of different non-empty subsets with
* the maximum bitwise OR. an array 'a' is a subset of an array 'b' if 'a' can
* be obtained from 'b' by deleting some (possibly 0) elements of 'b'. two
* subsets are considered different if the indices of the elements chosen are
* different. the bitwose OR of an array 'a' is equal to 'a[0] | a[1] | ... |
* a[n]' (0-indexed)
*/
void backtrack(int *nums, int numsSize, int target, int idx, int pos,
int *res) {
if (pos == numsSize)
return;
for (int i = pos; i < numsSize; i++) {
int tmp = idx | nums[i];
if (tmp == target)
(*res)++;
backtrack(nums, numsSize, target, tmp, i + 1, res);
}
}
int countMaxOrSubsets(int *nums, int numsSize) {
int max = 0, ans = 0;
for (int i = 0; i < numsSize; i++)
max |= nums[i];
for (int i = 0; i < numsSize; i++) {
if (nums[i] == max)
ans++;
backtrack(nums, numsSize, max, nums[i], i + 1, &ans);
}
return ans;
}
int main() {
int n1[] = {3, 1}, n2[] = {2, 2, 2}, n3[] = {3, 2, 1, 5};
printf("%d\n", countMaxOrSubsets(n1, ARRAY_SIZE(n1))); // expect: 2
printf("%d\n", countMaxOrSubsets(n2, ARRAY_SIZE(n2))); // expect: 7
printf("%d\n", countMaxOrSubsets(n3, ARRAY_SIZE(n3))); // expect: 6
}
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