LeetCode-in-Java

1546. Maximum Number of Non-Overlapping Subarrays With Sum Equals Target

Medium

Given an array nums and an integer target, return the maximum number of non-empty non-overlapping subarrays such that the sum of values in each subarray is equal to target.

Example 1:

Input: nums = [1,1,1,1,1], target = 2

Output: 2

Explanation: There are 2 non-overlapping subarrays [1,1,1,1,1] with sum equals to target(2).

Example 2:

Input: nums = [-1,3,5,1,4,2,-9], target = 6

Output: 2

Explanation: There are 3 subarrays with sum equal to 6. ([5,1], [4,2], [3,5,1,4,2,-9]) but only the first 2 are non-overlapping.

Constraints:

• 1 <= nums.length <= 105
• -104 <= nums[i] <= 104
• 0 <= target <= 106

Solution

import java.util.HashMap;
import java.util.Map;

public class Solution {
    public int maxNonOverlapping(int[] nums, int target) {
        int culSum = 0;
        int res = 0;
        Map<Integer, Integer> map = new HashMap<>();
        map.put(0, 0);
        for (int num : nums) {
            culSum += num;
            if (map.containsKey(culSum - target)) {
                res = Math.max(res, map.get(culSum - target) + 1);
            }
            map.put(culSum, res);
        }
        return res;
    }
}

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