Top 30 Array Interview Questions and Answers (2026)

1. Introduction to Array Interview Questions

Arrays are the most commonly tested data structure in coding interviews. Below are 30 essential array interview questions with complete solutions in C++, Java, Python, and JavaScript.

2. Easy Array Questions

Q1. Find Maximum Subarray Sum (Kadane's Algorithm)

cpp
int maxSubArray(vector<int>& nums) {
    int maxSum = nums[0], currSum = nums[0];
    for (size_t i = 1; i < nums.size(); i++) {
        currSum = max(nums[i], currSum + nums[i]);
        maxSum = max(maxSum, currSum);
    }
    return maxSum;
}

java
public int maxSubArray(int[] nums) {
    int maxSum = nums[0], currSum = nums[0];
    for (int i = 1; i < nums.length; i++) {
        currSum = Math.max(nums[i], currSum + nums[i]);
        maxSum = Math.max(maxSum, currSum);
    }
    return maxSum;
}

python
def maxSubArray(nums: list) -> int:
    max_sum = curr_sum = nums[0]
    for num in nums[1:]:
        curr_sum = max(num, curr_sum + num)
        max_sum = max(max_sum, curr_sum)
    return max_sum

javascript
function maxSubArray(nums) {
    let maxSum = nums[0], currSum = nums[0];
    for (let i = 1; i < nums.length; i++) {
        currSum = Math.max(nums[i], currSum + nums[i]);
        maxSum = Math.max(maxSum, currSum);
    }
    return maxSum;
}

Time Complexity: O(n) | Space Complexity: O(1)

Q2. Two Sum

cpp
vector<int> twoSum(vector<int>& nums, int target) {
    unordered_map<int, int> mp;
    for (int i = 0; i < nums.size(); i++) {
        int comp = target - nums[i];
        if (mp.count(comp)) return {mp[comp], i};
        mp[nums[i]] = i;
    }
    return {};
}

java
public int[] twoSum(int[] nums, int target) {
    Map<Integer, Integer> mp = new HashMap<>();
    for (int i = 0; i < nums.length; i++) {
        int comp = target - nums[i];
        if (mp.containsKey(comp)) return new int[]{mp.get(comp), i};
        mp.put(nums[i], i);
    }
    return new int[]{};
}

python
def twoSum(nums: list, target: int) -> list:
    mp = {}
    for i, num in enumerate(nums):
        comp = target - num
        if comp in mp: return [mp[comp], i]
        mp[num] = i
    return []

javascript
function twoSum(nums, target) {
    let mp = new Map();
    for (let i = 0; i < nums.length; i++) {
        let comp = target - nums[i];
        if (mp.has(comp)) return [mp.get(comp), i];
        mp.set(nums[i], i);
    }
    return [];
}

Time Complexity: O(n) | Space Complexity: O(n)

3. Summary Table

Practice all array problems on DSAMaster's practice platform.