1013. Partition Array Into Three Parts With Equal Sum

JIAKAOBO

LeetCode

感谢赞助!

• ㊗️
• 大家
• offer
• 多多！

Problem

Given an array of integers arr, return true 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 (arr[0] + arr[1] + … + arr[i] == arr[i + 1] + arr[i + 2] + … + arr[j - 1] == arr[j] + arr[j + 1] + … + arr[arr.length - 1])

Example 1:

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

Example 3:

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

Code

class Solution {
    public boolean canThreePartsEqualSum(int[] arr) {
        int sum = 0;
        for (int num : arr) {
            sum += num;
        }

        if (sum % 3 != 0) return false;

        int target = sum / 3;

        int curr = 0;
        int count = 0;
        for (int num : arr) {
            curr += num;
            if (curr == target) {
                curr = 0;
                count++;
            }
        }

        return count >= 3;
    }
}