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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
}
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