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-rw-r--r--count_num_max_or_subset.c43
1 files changed, 43 insertions, 0 deletions
diff --git a/count_num_max_or_subset.c b/count_num_max_or_subset.c
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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
+}