2824. Count Pairs Whose Sum is Less than Target LeetCode Solution

In this guide, you will get 2824. Count Pairs Whose Sum is Less than Target LeetCode Solution with the best time and space complexity. The solution to Count Pairs Whose Sum is Less than Target problem is provided in various programming languages like C++, Java, and Python. This will be helpful for you if you are preparing for placements, hackathons, interviews, or practice purposes. The solutions provided here are very easy to follow and include detailed explanations.

Table of Contents

  1. Problem Statement
  2. Complexity Analysis
  3. Count Pairs Whose Sum is Less than Target solution in C++
  4. Count Pairs Whose Sum is Less than Target solution in Java
  5. Count Pairs Whose Sum is Less than Target solution in Python
  6. Additional Resources
2824. Count Pairs Whose Sum is Less than Target LeetCode Solution image

Problem Statement of Count Pairs Whose Sum is Less than Target

Given a 0-indexed integer array nums of length n and an integer target, return the number of pairs (i, j) where 0 <= i < j < n and nums[i] + nums[j] < target.

Example 1:

Input: nums = [-1,1,2,3,1], target = 2
Output: 3
Explanation: There are 3 pairs of indices that satisfy the conditions in the statement:
– (0, 1) since 0 < 1 and nums[0] + nums[1] = 0 < target
– (0, 2) since 0 < 2 and nums[0] + nums[2] = 1 < target
– (0, 4) since 0 < 4 and nums[0] + nums[4] = 0 < target
Note that (0, 3) is not counted since nums[0] + nums[3] is not strictly less than the target.

Example 2:

Input: nums = [-6,2,5,-2,-7,-1,3], target = -2
Output: 10
Explanation: There are 10 pairs of indices that satisfy the conditions in the statement:
– (0, 1) since 0 < 1 and nums[0] + nums[1] = -4 < target
– (0, 3) since 0 < 3 and nums[0] + nums[3] = -8 < target
– (0, 4) since 0 < 4 and nums[0] + nums[4] = -13 < target
– (0, 5) since 0 < 5 and nums[0] + nums[5] = -7 < target
– (0, 6) since 0 < 6 and nums[0] + nums[6] = -3 < target
– (1, 4) since 1 < 4 and nums[1] + nums[4] = -5 < target
– (3, 4) since 3 < 4 and nums[3] + nums[4] = -9 < target
– (3, 5) since 3 < 5 and nums[3] + nums[5] = -3 < target
– (4, 5) since 4 < 5 and nums[4] + nums[5] = -8 < target
– (4, 6) since 4 < 6 and nums[4] + nums[6] = -4 < target

See also  2771. Longest Non-decreasing Subarray From Two Arrays LeetCode Solution

Constraints:

1 <= nums.length == n <= 50
-50 <= nums[i], target <= 50

Complexity Analysis

  • Time Complexity: O(n^2)
  • Space Complexity: O(1)

2824. Count Pairs Whose Sum is Less than Target LeetCode Solution in C++

class Solution {
 public:
  int countPairs(vector<int>& nums, int target) {
    int ans = 0;

    for (int i = 0; i < nums.size(); ++i)
      for (int j = i + 1; j < nums.size(); ++j)
        if (nums[i] + nums[j] < target)
          ++ans;

    return ans;
  }
};
/* code provided by PROGIEZ */

2824. Count Pairs Whose Sum is Less than Target LeetCode Solution in Java

class Solution {
  public int countPairs(List<Integer> nums, int target) {
    int ans = 0;

    for (int i = 0; i < nums.size(); ++i)
      for (int j = i + 1; j < nums.size(); ++j)
        if (nums.get(i) + nums.get(j) < target)
          ++ans;

    return ans;
  }
}
// code provided by PROGIEZ

2824. Count Pairs Whose Sum is Less than Target LeetCode Solution in Python

class Solution:
  def countPairs(self, nums: list[int], target: int) -> int:
    return sum(nums[i] + nums[j] < target
               for i in range(len(nums))
               for j in range(i + 1, len(nums)))
 # code by PROGIEZ

Additional Resources

Happy Coding! Keep following PROGIEZ for more updates and solutions.

Similar: