In this guide, you will get 724. Find Pivot Index LeetCode Solution with the best time and space complexity. The solution to Find Pivot Index 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.
Given an array of integers nums, calculate the pivot index of this array.
The pivot index is the index where the sum of all the numbers strictly to the left of the index is equal to the sum of all the numbers strictly to the index’s right.
If the index is on the left edge of the array, then the left sum is 0 because there are no elements to the left. This also applies to the right edge of the array.
Return the leftmost pivot index. If no such index exists, return -1.
Example 1:
Input: nums = [1,7,3,6,5,6]
Output: 3
Explanation:
The pivot index is 3.
Left sum = nums[0] + nums[1] + nums[2] = 1 + 7 + 3 = 11
Right sum = nums[4] + nums[5] = 5 + 6 = 11
Example 2:
Input: nums = [1,2,3]
Output: -1
Explanation:
There is no index that satisfies the conditions in the problem statement.
Example 3:
Input: nums = [2,1,-1]
Output: 0
Explanation:
The pivot index is 0.
Left sum = 0 (no elements to the left of index 0)
Right sum = nums[1] + nums[2] = 1 + -1 = 0
Note: This question is the same as 1991: https://leetcode.com/problems/find-the-middle-index-in-array/
Complexity Analysis
Time Complexity: O(n)
Space Complexity: O(1)
724. Find Pivot Index LeetCode Solution in C++
class Solution {
public:
int pivotIndex(vector<int>& nums) {
const int sum = accumulate(nums.begin(), nums.end(), 0);
int prefix = 0;
for (int i = 0; i < nums.size(); ++i) {
if (prefix == sum - prefix - nums[i])
return i;
prefix += nums[i];
}
return -1;
}
}; /* code provided by PROGIEZ */
724. Find Pivot Index LeetCode Solution in Java
class Solution {
public int pivotIndex(int[] nums) {
final int sum = Arrays.stream(nums).sum();
int prefix = 0;
for (int i = 0; i < nums.length; ++i) {
if (prefix == sum - prefix - nums[i])
return i;
prefix += nums[i];
}
return -1;
}
} // code provided by PROGIEZ
724. Find Pivot Index LeetCode Solution in Python
class Solution:
def pivotIndex(self, nums: list[int]) -> int:
summ = sum(nums)
prefix = 0
for i, num in enumerate(nums):
if prefix == summ - prefix - num:
return i
prefix += num
return -1 # code by PROGIEZ
