- Difficulty: Hard
- Tags: LeetCode, Hard, Array, Hash Table, Counting, Enumeration, Prefix Sum, leetcode-2025, O(n)
Problem
You are given a 0-indexed integer array nums
of length n
. The number of ways to partition nums
is the number of pivot
indices that satisfy both conditions:
1 <= pivot < n
nums[0] + nums[1] + ... + nums[pivot - 1] == nums[pivot] + nums[pivot + 1] + ... + nums[n - 1]
You are also given an integer k
. You can choose to change the value of one element of nums
to k
, or to leave the array unchanged.
Return the maximum possible number of ways to partition nums
to satisfy both conditions after changing at most one element.
Example 1:
Input: nums = [2,-1,2], k = 3 Output: 1 Explanation: One optimal approach is to change nums[0] to k. The array becomes [3,-1,2]. There is one way to partition the array: - For pivot = 2, we have the partition [3,-1 | 2]: 3 + -1 == 2.
Example 2:
Input: nums = [0,0,0], k = 1 Output: 2 Explanation: The optimal approach is to leave the array unchanged. There are two ways to partition the array: - For pivot = 1, we have the partition [0 | 0,0]: 0 == 0 + 0. - For pivot = 2, we have the partition [0,0 | 0]: 0 + 0 == 0.
Example 3:
Input: nums = [22,4,-25,-20,-15,15,-16,7,19,-10,0,-13,-14], k = -33 Output: 4 Explanation: One optimal approach is to change nums[2] to k. The array becomes [22,4,-33,-20,-15,15,-16,7,19,-10,0,-13,-14]. There are four ways to partition the array.
Constraints:
n == nums.length
2 <= n <= 105
-105 <= k, nums[i] <= 105