Blogs Hub

How Many Numbers Are Smaller Than the Current Number - Array - Easy - LeetCode - MiniTV

How Many Numbers Are Smaller Than the Current Number - Array - Easy - LeetCode - मिनी टीवी

Given the array nums, for each nums[i] find out how many numbers in the array are smaller than it. That is, for each nums[i] you have to count the number of valid j's such that j != i and nums[j] < nums[i].

Return the answer in an array.

 

Example 1:

Input: nums = [8,1,2,2,3]

Output: [4,0,1,1,3]

Explanation: 

For nums[0]=8 there exist four smaller numbers than it (1, 2, 2 and 3). 

For nums[1]=1 does not exist any smaller number than it.

For nums[2]=2 there exist one smaller number than it (1). 

For nums[3]=2 there exist one smaller number than it (1). 

For nums[4]=3 there exist three smaller numbers than it (1, 2 and 2).

 

Example 2:

Input: nums = [6,5,4,8]

Output: [2,1,0,3]

 

Example 3:

Input: nums = [7,7,7,7]

Output: [0,0,0,0]

 

Constraints:

2 <= nums.length <= 500

0 <= nums[i] <= 100

 

Solution:

using System;
using System.Collections.Generic;
using System.Text;

namespace LeetCode.AskGif.Easy.Array
{
    public class SmallerNumbersThanCurrentSoln
    {
        public int[] SmallerNumbersThanCurrent(int[] nums)
        {
            var res = new int[nums.Length];
            for (int i = 0; i < nums.Length; i++)
            {
                res[i] = 0;
                for (int j = 0; j < nums.Length; j++)
                {
                    if (nums[i] > nums[j])
                    {
                        res[i]++;
                    }
                }
            }

            return res;
        }
    }
}

Time Complexity: O(n^2)

Space Complexity: O(n) To Store Result

 

Unit Tests:

using LeetCode.AskGif.Easy.Array;
using Microsoft.VisualStudio.TestTools.UnitTesting;
using System;
using System.Collections.Generic;
using System.Text;

namespace CodingUnitTest.Easy.Array
{
    [TestClass]
    public class SmallerNumbersThanCurrentSolnTests
    {
        [TestMethod]
        public void SmallerNumbersThanCurrentSoln_First()
        {
            var nums = new int[] { 8, 1, 2, 2, 3 };
            var output = new int[]{4, 0, 1, 1, 3};
            var res = new SmallerNumbersThanCurrentSoln().SmallerNumbersThanCurrent(nums);

            AreEqual(res, output);
        }

        [TestMethod]
        public void SmallerNumbersThanCurrentSoln_Second()
        {
            var nums = new int[] { 6, 5, 4, 8 };
            var output = new int[] { 2, 1, 0, 3 };
            var res = new SmallerNumbersThanCurrentSoln().SmallerNumbersThanCurrent(nums);

            AreEqual(res, output);
        }

        [TestMethod]
        public void SmallerNumbersThanCurrentSoln_Third()
        {
            var nums = new int[] { 7, 7, 7, 7 };
            var output = new int[] { 0, 0, 0, 0 };
            var res = new SmallerNumbersThanCurrentSoln().SmallerNumbersThanCurrent(nums);

            AreEqual(res, output);
        }
        private void AreEqual(int[] res, int[] output)
        {
            Assert.AreEqual(res.Length, output.Length);
            for (int i = 0; i < res.Length; i++)
            {
                Assert.AreEqual(res[i], output[i]);
            }
        }
    }
}