3354. Make Array Elements Equal to Zero LeetCode Solution

Last updated: March 6, 2025

In this guide, you will get 3354. Make Array Elements Equal to Zero LeetCode Solution with the best time and space complexity. The solution to Make Array Elements Equal to Zero problem is provided in various programming languages like C++, Java, and Python. This will be helpful for you if you are preparing for placements, hackathons, interviews, or practice purposes. The solutions provided here are very easy to follow and include detailed explanations.

Problem Statement
Complexity Analysis
Make Array Elements Equal to Zero solution in C++
Make Array Elements Equal to Zero solution in Java
Make Array Elements Equal to Zero solution in Python
Additional Resources

3354. Make Array Elements Equal to Zero LeetCode Solution image

Problem Statement of Make Array Elements Equal to Zero

You are given an integer array nums.
Start by selecting a starting position curr such that nums[curr] == 0, and choose a movement direction of either left or right.
After that, you repeat the following process:

If curr is out of the range [0, n – 1], this process ends.
If nums[curr] == 0, move in the current direction by incrementing curr if you are moving right, or decrementing curr if you are moving left.
Else if nums[curr] > 0:

Decrement nums[curr] by 1.
Reverse your movement direction (left becomes right and vice versa).
Take a step in your new direction.

A selection of the initial position curr and movement direction is considered valid if every element in nums becomes 0 by the end of the process.
Return the number of possible valid selections.

Example 1:

Input: nums = [1,0,2,0,3]
Output: 2
Explanation:
The only possible valid selections are the following:

Choose curr = 3, and a movement direction to the left.

[1,0,2,0,3] -> [1,0,2,0,3] -> [1,0,1,0,3] -> [1,0,1,0,3] -> [1,0,1,0,2] -> [1,0,1,0,2] -> [1,0,0,0,2] -> [1,0,0,0,2] -> [1,0,0,0,1] -> [1,0,0,0,1] -> [1,0,0,0,1] -> [1,0,0,0,1] -> [0,0,0,0,1] -> [0,0,0,0,1] -> [0,0,0,0,1] -> [0,0,0,0,1] -> [0,0,0,0,0].

Choose curr = 3, and a movement direction to the right.

[1,0,2,0,3] -> [1,0,2,0,3] -> [1,0,2,0,2] -> [1,0,2,0,2] -> [1,0,1,0,2] -> [1,0,1,0,2] -> [1,0,1,0,1] -> [1,0,1,0,1] -> [1,0,0,0,1] -> [1,0,0,0,1] -> [1,0,0,0,0] -> [1,0,0,0,0] -> [1,0,0,0,0] -> [1,0,0,0,0] -> [0,0,0,0,0].

Example 2:

Input: nums = [2,3,4,0,4,1,0]
Output: 0
Explanation:
There are no possible valid selections.

Constraints:

1 <= nums.length <= 100
0 <= nums[i] <= 100
There is at least one element i where nums[i] == 0.

Complexity Analysis

Time Complexity: O(n)
Space Complexity: O(n)

3354. Make Array Elements Equal to Zero LeetCode Solution in C++

class Solution {
 public:
  int countValidSelections(vector<int>& nums) {
    const int n = nums.size();
    int ans = 0;
    vector<int> prefix(n);  // sum(nums[0..i - 1])
    vector<int> suffix(n);  // sum(nums[i + 1..n - 1])

    for (int i = 1; i < n; ++i)
      prefix[i] = prefix[i - 1] + nums[i - 1];

    for (int i = n - 2; i >= 0; --i)
      suffix[i] = suffix[i + 1] + nums[i + 1];

    for (int i = 0; i < n; ++i) {
      if (nums[i] > 0)
        continue;
      if (prefix[i] == suffix[i])
        ans += 2;  // Go to either direction.
      if (abs(prefix[i] - suffix[i]) == 1)
        ans += 1;  // Go to the direction with the larger sum.
    }

    return ans;
  }
};
/* code provided by PROGIEZ */

3354. Make Array Elements Equal to Zero LeetCode Solution in Java

class Solution {
  public int countValidSelections(int[] nums) {
    final int n = nums.length;
    int ans = 0;
    int[] prefix = new int[n]; // sum(nums[0..i - 1])
    int[] suffix = new int[n]; // sum(nums[i + 1..n - 1])

    for (int i = 1; i < n; ++i)
      prefix[i] = prefix[i - 1] + nums[i - 1];

    for (int i = n - 2; i >= 0; --i)
      suffix[i] = suffix[i + 1] + nums[i + 1];

    for (int i = 0; i < n; ++i) {
      if (nums[i] > 0)
        continue;
      if (prefix[i] == suffix[i])
        ans += 2; // Go to either direction.
      if (Math.abs(prefix[i] - suffix[i]) == 1)
        ans += 1; // Go to the direction with the larger sum.
    }

    return ans;
  }
}
// code provided by PROGIEZ

3354. Make Array Elements Equal to Zero LeetCode Solution in Python

class Solution:
  def countValidSelections(self, nums: list[int]) -> int:
    ans = 0
    prefix = list(itertools.accumulate(nums))
    suffix = list(itertools.accumulate(nums[::-1]))[::-1]

    for i, num in enumerate(nums):
      if num > 0:
        continue
      if prefix[i] == suffix[i]:
        ans += 2  # Go to either direction.
      if abs(prefix[i] - suffix[i]) == 1:
        ans += 1  # Go to the direction with the larger sum.

    return ans
 # code by PROGIEZ

Additional Resources

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