// 1524. Number of Sub-arrays With Odd Sum #include "leetcode.h" /* * given an array of integers 'arr', return the number of subarrays with an odd * sum. since the answer can be very large, return it modulo 10e9+7. */ int numOfSubarrays(int *arr, int arrSize) { int curr = 0, ans = 0, cnt[] = {1, 0}, mod = 1e9 + 7; for (int i = 0; i < arrSize; i++) { curr ^= arr[i] & 1; ans = (ans + cnt[1 - curr]) % mod; cnt[curr]++; } return ans; } int main() { int a1[] = {1, 3, 5}, a2[] = {2, 4, 6}, a3[] = {1, 2, 3, 4, 5, 6, 7}; printf("%d\n", numOfSubarrays(a1, ARRAY_SIZE(a1))); // expect: 4 printf("%d\n", numOfSubarrays(a2, ARRAY_SIZE(a2))); // expect: 0 printf("%d\n", numOfSubarrays(a3, ARRAY_SIZE(a3))); // expect: 16 }