1013. Partition Array Into Three Parts With Equal Sum.md

1013. Partition Array Into Three Parts With Equal Sum

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Difficulty : Easy

Related Topics : Array

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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])

Example 1:

Input: A = [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

Example 2:

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

Example 3:

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

Constraints:

• 3 <= A.length <= 50000
• -10^4 <= A[i] <= 10^4

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Solution

• mine
  • Java
    • Runtime: 1 ms, faster than 100.00%, Memory Usage: 46.7 MB, less than 10.13% of Java online submissions

      // O(N)time
      // O(1)space
      public boolean canThreePartsEqualSum(int[] A) {
          int sum = 0;
          for(int a : A) sum += a;
          double t = sum * 1.0D / 3;
          int c = 0;
          int temp = 0;
          for(int a : A){
              temp += a;
              if(temp == t) {
                  c++;
                  temp = 0;
              }
          }
          return c >= 3 && temp == 0;
      }
      

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