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]);
}
}
}
}
