Given an array of integers, find the smallest number after deleting given elements. In case of repeating elements, we delete one instance (from the original array) for every instance present in the array containing elements to be deleted.

**Examples:**

Input : Array = {5, 12, 33, 4, 56, 12, 20}

To Delete = {12, 4, 56, 5}

Output : 12

After deleting given elements, array becomes {33, 12, 20} and minimum element becomes 12. Note that there are two occurrences of 12 and we delete one of them.Input : Array = {1, 20, 3, 4, 10}

To Delete = {1, 4, 10}

Output : 3

**Approach :**

- Insert all the numbers in the hash map which are to be deleted from the array, so that we can check if the element in the array is also present in the Delete-array in O(1) time.
- Initialize smallest number min to be INT_MAX.
- Traverse through the array. Check if the element is present in the hash map.
- If present, erase it from the hash map, else if not present compare it with min variable and change its value if the value of the element is less than the min value.

## C++

`// C++ program to find the smallest number ` `// from the array after n deletions ` `#include "climits" ` `#include "iostream" ` `#include "unordered_map" ` `using` `namespace` `std; ` ` ` `// Returns minimum element from arr[0..m-1] after deleting ` `// elements from del[0..n-1] ` `int` `findSmallestAfterDel(` `int` `arr[], ` `int` `m, ` `int` `del[], ` `int` `n) ` `{ ` ` ` `// Hash Map of the numbers to be deleted ` ` ` `unordered_map<` `int` `, ` `int` `> mp; ` ` ` `for` `(` `int` `i = 0; i < n; ++i) { ` ` ` ` ` `// Increment the count of del[i] ` ` ` `mp[del[i]]++; ` ` ` `} ` ` ` ` ` `// Initializing the smallestElement ` ` ` `int` `smallestElement = INT_MAX; ` ` ` ` ` `for` `(` `int` `i = 0; i < m; ++i) { ` ` ` ` ` `// Search if the element is present ` ` ` `if` `(mp.find(arr[i]) != mp.end()) { ` ` ` ` ` `// Decrement its frequency ` ` ` `mp[arr[i]]--; ` ` ` ` ` `// If the frequency becomes 0, ` ` ` `// erase it from the map ` ` ` `if` `(mp[arr[i]] == 0) ` ` ` `mp.erase(arr[i]); ` ` ` `} ` ` ` ` ` `// Else compare it smallestElement ` ` ` `else` ` ` `smallestElement = min(smallestElement, arr[i]); ` ` ` `} ` ` ` ` ` `return` `smallestElement; ` `} ` ` ` `int` `main() ` `{ ` ` ` `int` `array[] = { 5, 12, 33, 4, 56, 12, 20 }; ` ` ` `int` `m = ` `sizeof` `(array) / ` `sizeof` `(array[0]); ` ` ` ` ` `int` `del[] = { 12, 4, 56, 5 }; ` ` ` `int` `n = ` `sizeof` `(del) / ` `sizeof` `(del[0]); ` ` ` ` ` `cout << findSmallestAfterDel(array, m, del, n); ` ` ` `return` `0; ` `} ` |

*chevron_right*

*filter_none*

## Python3

# Python3 program to find the smallest

# number from the array after n deletions

import math as mt

# Returns maximum element from arr[0..m-1]

# after deleting elements from del[0..n-1]

def findSmallestAfterDel(arr, m, dell, n):

# Hash Map of the numbers

# to be deleted

mp = dict()

for i in range(n):

# Increment the count of del[i]

if dell[i] in mp.keys():

mp[dell[i]] += 1

else:

mp[dell[i]] = 1

# Initializing the SmallestElement

SmallestElement = 10**9

for i in range(m):

# Search if the element is present

if (arr[i] in mp.keys()):

# Decrement its frequency

mp[arr[i]] -= 1

# If the frequency becomes 0,

# erase it from the map

if (mp[arr[i]] == 0):

mp.pop(arr[i])

# Else compare it SmallestElement

else:

SmallestElement = min(SmallestElement,

arr[i])

return SmallestElement

# Driver code

array = [5, 12, 33, 4, 56, 12, 20]

m = len(array)

dell = [12, 4, 56, 5]

n = len(dell)

print(findSmallestAfterDel(array, m, dell, n))

# This code is contributed

# by mohit kumar 29

**Output:**

12

**Time Complexity** – O(N)

## Recommended Posts:

- Find the k smallest numbers after deleting given elements
- Find the largest after deleting the given elements
- Find the k largest numbers after deleting the given elements
- Find maximum points which can be obtained by deleting elements from array
- Find the smallest and second smallest elements in an array
- Find smallest range containing elements from k lists
- Find smallest subarray that contains all elements in same order
- Program to find the smallest element among three elements
- Find the Largest Cube formed by Deleting minimum Digits from a number
- Average of remaining elements after removing K largest and K smallest elements from array
- Find last element after deleting every second element in array of n integers
- Smallest subarray such that all elements are greater than K
- Smallest subset with sum greater than all other elements
- Smallest greater elements in whole array
- k-th smallest absolute difference of two elements in an array

If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.