// 995. Minimum Number of K Consecutive Bit Flips #include "leetcode.h" /* * given a binary array 'nums', and an integer 'k'. a k-bit flip is choosing a * subarray of length 'k' from 'nums' and simultaneously changing every 0 in the * subarray to 1, and every 1 in the subarray to 0. return the minimum number of * k-bit flips required so that there is no 0 in the array. if it is not * possible, return -1. a subarray is a contiguous part of an array. */ int minKBitFlips(int *nums, int numsSize, int k) { int ans = 0, n = numsSize; int *dp = (int *)calloc(n + 2 * k, sizeof(int)); for (int i = 0; i < n; i++) { dp[i + k] += dp[i + k - 1]; if (!nums[i] && !(dp[i + 2] % 2)) { if (n - i < k) return -1; ans++; dp[i + k]++; dp[i + k + k]--; } else if (nums[i] && dp[i + k] % 2 == 1) { if (n - i < k) return -1; ans++; dp[i + k]++; dp[i + k + k]--; } } free(dp); return ans; } int main() { int n1[] = {0, 1, 0}, n2[] = {1, 1, 0}, n3[] = {0, 0, 0, 1, 0, 1, 1, 0}; printf("%d\n", minKBitFlips(n1, ARRAY_SIZE(n1), 1)); // expect: 2 printf("%d\n", minKBitFlips(n2, ARRAY_SIZE(n2), 2)); // expect: -1 printf("%d\n", minKBitFlips(n3, ARRAY_SIZE(n3), 3)); // expect: 3 }