Replace every element with the smallest element on its left side
Given an array of integers, the task is to replace every element with the smallest element on its left side.
Note: Replace the first element with -1 as it has no element in its left.
Examples:
Input: arr[] = {4, 5, 2, 1, 7, 6} Output: -1 4 4 2 1 1 Since, 4 has no element in its left, so replace it by -1. For 5, 4 is the smallest element in its left. For 2, 4 is the smallest element in its left. For 1, 2 is the smallest element in its left. For 7, 1 is the smallest element in its left. For 6, 1 is the smallest element in its left. Input: arr[] = {3, 2, 5, 7, 1} Output: -1 3 2 2 2
Approach:
- Maintain a variable min_ele which will store the smallest element.
- Initially, min_ele will be equal to the element at the 0th index.
- First replace arr[0] with -1 then traverse the array
- And then replace the element with the min_ele value and update the min_ele if the element is smaller than min_ele.
- Print the modified array.
Below is the implementation of the above approach:
C++
// C++ program to Replace every // element with the smaller element // on its left side #include <bits/stdc++.h> using namespace std; // Function to replace the elements void ReplaceElements( int arr[], int n) { // MIN value initialised // to element at 0th index int min_ele = arr[0]; arr[0] = -1; for ( int i = 1; i < n; ++i) { // If min_ele is smaller than arr[i] // then just replace arr[i] with min_ele if (min_ele < arr[i]) arr[i] = min_ele; // Else if update the min_ele also else if (min_ele >= arr[i]) { int temp = arr[i]; arr[i] = min_ele; min_ele = temp; } } } // Driver code int main() { int arr[] = { 4, 5, 2, 1, 7, 6 }; int n = sizeof (arr) / sizeof (arr[0]); // Replace the elements // with the smaller element // on its left side ReplaceElements(arr, n); // Print the modified array for ( int i = 0; i < n; ++i) cout << arr[i] << " " ; return 0; } |
Java
// Java program to Replace every // element with the smaller element // on its left side class GFG { // Function to replace the elements static void ReplaceElements( int arr[], int n) { // MIN value initialised // to element at 0th index int min_ele = arr[ 0 ]; arr[ 0 ] = - 1 ; for ( int i = 1 ; i < n; ++i) { // If min_ele is smaller than arr[i] // then just replace arr[i] with min_ele if (min_ele < arr[i]) { arr[i] = min_ele; } // Else if update the min_ele also else if (min_ele >= arr[i]) { int temp = arr[i]; arr[i] = min_ele; min_ele = temp; } } } // Driver code public static void main(String[] args) { int arr[] = { 4 , 5 , 2 , 1 , 7 , 6 }; int n = arr.length; // Replace the elements // with the smaller element // on its left side ReplaceElements(arr, n); // Print the modified array for ( int i = 0 ; i < n; ++i) { System.out.print(arr[i] + " " ); } } } // This code is contributed by Rajput-JI |
Python3
# Python3 program to Replace every # element with the smaller element # on its left side # Function to replace the elements def ReplaceElements(arr, n): # MIN value initialised # to element at 0th index min_ele = arr[ 0 ] arr[ 0 ] = - 1 for i in range ( 1 , n): # If min_ele is smaller than arr[i] # then just replace arr[i] with min_ele if (min_ele < arr[i]): arr[i] = min_ele # Else if update the min_ele also elif (min_ele > = arr[i]) : temp = arr[i] arr[i] = min_ele min_ele = temp # Driver code if __name__ = = "__main__" : arr = [ 4 , 5 , 2 , 1 , 7 , 6 ] n = len (arr) # Replace the elements # with the smaller element # on its left side ReplaceElements(arr, n) # Print the modified array for i in range ( n): print (arr[i], end = " " ) # This code is contributed # by ChitraNayal |
C#
// C# program to Replace every // element with the smaller element // on its left side using System; public class GFG { // Function to replace the elements static void ReplaceElements( int []arr, int n) { // MIN value initialised // to element at 0th index int min_ele = arr[0]; arr[0] = -1; for ( int i = 1; i < n; ++i) { // If min_ele is smaller than arr[i] // then just replace arr[i] with min_ele if (min_ele < arr[i]) { arr[i] = min_ele; } // Else if update the min_ele also else if (min_ele >= arr[i]) { int temp = arr[i]; arr[i] = min_ele; min_ele = temp; } } } // Driver code public static void Main() { int []arr = {4, 5, 2, 1, 7, 6}; int n = arr.Length; // Replace the elements // with the smaller element // on its left side ReplaceElements(arr, n); // Print the modified array for ( int i = 0; i < n; ++i) { Console.Write(arr[i] + " " ); } } } // This code is contributed by Rajput-JI |
PHP
<?php // PHP program to Replace every // element with the smaller element // on its left side // Function to replace the elements function ReplaceElements( $arr , $n ) { // MIN value initialised // to element at 0th index $min_ele = $arr [0]; $arr [0] = -1; for ( $i = 1; $i < $n ; ++ $i ) { // If min_ele is smaller than arr[i] // then just replace arr[i] with min_ele if ( $min_ele < $arr [ $i ]) $arr [ $i ] = $min_ele ; // Else if update the min_ele also else if ( $min_ele >= $arr [ $i ]) { $temp = $arr [ $i ]; $arr [ $i ] = $min_ele ; $min_ele = $temp ; } } return $arr ; } // Driver code $arr = array (4, 5, 2, 1, 7, 6); $n = sizeof( $arr ); // Replace the elements // with the smaller element // on its left side $arr1 = ReplaceElements( $arr , $n ); // Print the modified array for ( $i = 0; $i < $n ; ++ $i ) echo $arr1 [ $i ] . " " ; // This code is contributed // by Akanksha Rai ?> |
Javascript
<script> // JavaScript program to Replace every // element with the smaller element // on its left side // Function to replace the elements function ReplaceElements(arr, n) { // MIN value initialised // to element at 0th index var min_ele = arr[0]; arr[0] = -1; for ( var i = 1; i < n; ++i) { // If min_ele is smaller than arr[i] // then just replace arr[i] with min_ele if (min_ele < arr[i]) arr[i] = min_ele; // Else if update the min_ele also else if (min_ele >= arr[i]) { var temp = arr[i]; arr[i] = min_ele; min_ele = temp; } } } // Driver code var arr = [4, 5, 2, 1, 7, 6]; var n = arr.length; // Replace the elements // with the smaller element // on its left side ReplaceElements(arr, n); // Print the modified array for ( var i = 0; i < n; ++i) document.write(arr[i] + " " ); // This code is contributed by rdtank. </script> |
Output:
-1 4 4 2 1 1
Time Complexity: O(N)