2134. Minimum Swaps to Group All 1's Together II
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Topics
A swap is defined as taking two distinct positions in an array and swapping the values in them.
A circular array is defined as an array where we consider the first element and the last element to be adjacent.
Given a binary circular array nums, return the minimum number of swaps required to group all 1's present in the array together at any location.
Example 1:
Input: nums = [0,1,0,1,1,0,0] Output: 1 Explanation: Here are a few of the ways to group all the 1's together: [0,0,1,1,1,0,0] using 1 swap. [0,1,1,1,0,0,0] using 1 swap. [1,1,0,0,0,0,1] using 2 swaps (using the circular property of the array). There is no way to group all 1's together with 0 swaps. Thus, the minimum number of swaps required is 1.
Example 2:
Input: nums = [0,1,1,1,0,0,1,1,0] Output: 2 Explanation: Here are a few of the ways to group all the 1's together: [1,1,1,0,0,0,0,1,1] using 2 swaps (using the circular property of the array). [1,1,1,1,1,0,0,0,0] using 2 swaps. There is no way to group all 1's together with 0 or 1 swaps. Thus, the minimum number of swaps required is 2.
Example 3:
Input: nums = [1,1,0,0,1] Output: 0 Explanation: All the 1's are already grouped together due to the circular property of the array. Thus, the minimum number of swaps required is 0.
Constraints:
1 <= nums.length <= 105nums[i]is either0or1.
Hints
Hint 1
Notice that the number of 1’s to be grouped together is fixed. It is the number of 1's the whole array has.
Hint 2
Call this number total. We should then check for every subarray of size total (possibly wrapped around), how many swaps are required to have the subarray be all 1’s.
Hint 3
The number of swaps required is the number of 0’s in the subarray.
Hint 4
To eliminate the circular property of the array, we can append the original array to itself. Then, we check each subarray of length total.
Hint 5
How do we avoid recounting the number of 0’s in the subarray each time? The Sliding Window technique can help.