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authorjack <[email protected]>2024-06-14 13:13:15 -0600
committerjack <[email protected]>2024-06-14 13:13:15 -0600
commitd343a3b18dbaca9297d4f7b2280c4a16f0a5c8aa (patch)
tree96df922dae2a5073d9a50ea70c7aae6aa37e3ebe /binary_subarr_sum.c
downloadleetcode-d343a3b18dbaca9297d4f7b2280c4a16f0a5c8aa.tar.gz
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+// 930. Binary Subarrays With Sum
+#include "leetcode.h"
+
+/*
+ * given a binary array 'nums' and an integer 'goal', return the number o
+ * non-empty subarrays with a sum 'goal'. a subarray is a contiguous part of the
+ * array
+ */
+
+int numSubarraysWithSum(int *nums, int numsSize, int goal) {
+ int n = numsSize, m = n + 1, sum = 0, rm, d, ans = 0;
+ int **hash = calloc(m, sizeof(int *));
+ hash[0] = malloc(2 * sizeof(int));
+ hash[0][0] = 0;
+ hash[0][1] = 1;
+ for (int i = 0; i < n; i++) {
+ sum += nums[i];
+ rm = sum - goal;
+ d = rm;
+ while (1 && rm >= 0) {
+ if (hash[d % n] == NULL)
+ break;
+ else if (hash[d % n][0] == rm) {
+ ans += hash[d % n][1];
+ break;
+ } else {
+ d++;
+ }
+ }
+ d = sum;
+ while (1) {
+ if (hash[d % n] == NULL) {
+ hash[d % n] = malloc(2 * sizeof(int));
+ hash[d % n][0] = sum;
+ hash[d % n][1] = 1;
+ break;
+ } else if (hash[d % n][0] == sum) {
+ hash[d % n][1]++;
+ break;
+ } else {
+ d++;
+ }
+ }
+ }
+ return ans;
+}
+
+int main() {
+ int n1[] = {1, 0, 1, 0, 1}, n2[] = {0, 0, 0, 0, 0};
+ printf("%d\n", numSubarraysWithSum(n1, ARRAY_SIZE(n1), 2)); // expect: 4
+ printf("%d\n", numSubarraysWithSum(n2, ARRAY_SIZE(n2), 0)); // expect: 15
+}