Immediate Smaller Element | Practice | GeeksforGeeks

Given an integer array Arr of size N. For each element in the array, check whether the right adjacent element (on the next immediate position) of the array is smaller. If next element is smaller, update the current index to that element. If not, then  -1.
Example 1:
Input:
N = 5
Arr[] = {4, 2, 1, 5, 3}
Output:
2 1 -1 3 -1
Explanation: Array elements are 4, 2, 1, 5
3. Next to 4 is 2 which is smaller, so we
print 2. Next of 2 is 1 which is smaller,
so we print 1. Next of 1 is 5 which is
greater, so we print -1. Next of 5 is 3
which is smaller, so we print 3.  Note
that for last element, output is always 
going to be -1 because there is no element
on right.
Example 2:
Input:
N = 6
Arr[] = {5, 6, 2, 3, 1, 7}
Output:
-1 2 -1 1 -1 -1
Explanation: Next to 5 is 6 which is
greater, so we print -1.Next of 6 is 2
which is smaller, so we print 2. Next
of 2 is 3 which is greater, so we
print -1. Next of 3 is 1 which is
smaller, so we print 1. Next of 1 is
7 which is greater, so we print -1.
Note that for last element, output is
always going to be -1 because there is
no element on right.
Your Task:  
You don't need to read input or print anything. Your task is to complete the function immediateSmaller() which takes the array of integers arr and n as parameters. You need to change the array itself.
Expected Time Complexity: O(N)
Expected Auxiliary Space: O(1)
Constraints:
1 ≤ N ≤ 107
1 ≤ Arr[i] ≤ 105
 
0
mayank180919991 week ago
	void immediateSmaller(int *arr, int n) {
	    //  code here
	    for(int i=1;i<n;i++){
	       if(arr[i-1]>arr[i]){
	           arr[i-1]=arr[i];
	       }else{
	           arr[i-1]=-1;
	       } 
	    }
	    arr[n-1]=-1;
	}
0
amanahirwar1511 week ago
C++ STACK SOLUTIONvoid immediateSmaller(int *arr, int n) {       stack<int> st;       for(int i=n-1; i>=0; i--){           int a;           if(!st.empty() && st.top()<arr[i]){               a=arr[i];               arr[i]=st.top();               st.pop();           }else{               a=arr[i];               arr[i]=-1;           }           st.push(a);       }} 
0
sujeetkr25082 weeks ago
Python Solution
class Solution:
   def immediateSmaller(self,arr,n):        # code here        for i in range(0, n - 1, 1):            if arr[i] > arr[i+1]:                arr[i] = arr[i+1]         else:              arr[i] = -1    arr[n-1] = -1    return arr     
 
0
ravigupta355162 weeks ago
Java Solution using Stack
Stack<Integer> s = new Stack<>();       for(int i=0; i<n-1; i++){           s.push(arr[i]);           if(s.peek() > arr[i+1]){               arr[i] = arr[i+1];           }else{               arr[i] = -1;           }       }       arr[n-1] = -1;
0
kanup19031 month ago
// very easy solution in c++;
 void immediateSmaller(int *arr, int n) {    //  code here             int j=1;              int i;        for( i=0;i<n-1;i++)            {                   if(arr[i]>arr[j])                        {                            arr[i]=arr[j];                            j++;                        }                    else                        {                              arr[i]=-1;                                j++;                       }            }           arr[i]=-1;}
};
0
hasnainraza1998hr1 month ago
C++, 0.4
void immediateSmaller(int *arr, int n) {    for(int i=0;i<n-1;i++){        if(arr[i+1]<arr[i])            arr[i]=arr[i+1];        else            arr[i]=-1;    }    arr[n-1]=-1;}
0
tarunlella20001 month ago
//java using stack 
class Solution {   void immediateSmaller(int arr[], int n) {       // code here       Stack<Integer> s = new Stack<>();       for(int i =n-1; i>=0; i--){           int a;           if(!s.isEmpty() && s.peek() < arr[i]){               a = arr[i];               arr[i] = s.pop();                          }           else{               a = arr[i];               arr[i] = -1;           }                      s.push(a);       }   }}
0
0niharika22 months ago
for(int i=0; i<n-1; i++)    {        if(arr[i+1]<arr[i])            arr[i] = arr[i+1];        else            arr[i] = -1;    }    arr[n-1] = -1;
0
surabhichoubey552 months ago
 void immediateSmaller(int *arr, int n) {    //  code her    int i;    for( i = 0;i<n-1;i++)    {                    if(arr[i] > arr[i+1])            {                int temp = arr[i+1];                arr[i] = temp;            }            else            {                arr[i] = -1;            }                        }    arr[i] = -1;        } 
+1
dipanshusharma93132 months ago
class Solution {   void immediateSmaller(int arr[], int n) {       // code here       int array [] = new int [n];       for(int i=0;i<n-1;i++){           if(arr[i]>arr[i+1]){              arr[i] = arr[i+1];           }           else{              arr[i] = -1;           }       }      arr[n-1] = -1;   }}
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