LC-1013 - Partition Array Into Three Parts With Equal Sum

Given an array A of integers, return true if and only if we can partition the array into three non-empty parts with equal sums.

Formally, we can partition the array if we can find indexes i + 1 < j with (A[0] + A[1] + ... + A[i] == A[i+1] + A[i+2] + ... + A[j-1] == A[j] + A[j-1] + ... + A[A.length - 1]).

• Difficulty: EASY

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Examples

Input: [0,2,1,-6,6,-7,9,1,2,0,1]
Output: true
Explanation:
0 + 2 + 1 = -6 + 6 - 7 + 9 + 1 = 2 + 0 + 1

Input: [0,2,1,-6,6,7,9,-1,2,0,1]
Output: false

Input: [3,3,6,5,-2,2,5,1,-9,4]
Output: true
Explanation:
3 + 3 = 6 = 5 - 2 + 2 + 5 + 1 - 9 + 4

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Notes

• 3 <= A.length <= 50000
• -10000 <= A[i] <= 10000

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Solutions

1. Counting
   • Time complexity: $O(n)$
   • Space complexity: $O(1)$