From 9c1ac04eaba8dfe123ec720fca01f4fac4576f5a Mon Sep 17 00:00:00 2001
From: manan-shxrma <78374257+manan-shxrma@users.noreply.github.com>
Date: Fri, 1 Oct 2021 22:34:31 +0530
Subject: [PATCH] Create pigeonhole_sort
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this a sorting algorithm that is suitable for sorting lists of elements where the number of elements and the number of possible key values are approximately the same.
It requires O(n + Range) time where n is number of elements in input array and ‘Range’ is number of possible values in array.
---
 Arrays/pigeonhole_sort | 53 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 53 insertions(+)
 create mode 100644 Arrays/pigeonhole_sort

diff --git a/Arrays/pigeonhole_sort b/Arrays/pigeonhole_sort
new file mode 100644
index 0000000..83743c7
--- /dev/null
+++ b/Arrays/pigeonhole_sort
@@ -0,0 +1,53 @@
+#include <bits/stdc++.h>
+using namespace std;
+ 
+/* Sorts the array using pigeonhole algorithm */
+void pigeonholeSort(int arr[], int n)
+{
+    // Find minimum and maximum values in arr[]
+    int min = arr[0], max = arr[0];
+    for (int i = 1; i < n; i++)
+    {
+        if (arr[i] < min)
+            min = arr[i];
+        if (arr[i] > max)
+            max = arr[i];
+    }
+    int range = max - min + 1; // Find range
+ 
+    // Create an array of vectors. Size of array
+    // range. Each vector represents a hole that
+    // is going to contain matching elements.
+    vector<int> holes[range];
+ 
+    // Traverse through input array and put every
+    // element in its respective hole
+    for (int i = 0; i < n; i++)
+        holes[arr[i]-min].push_back(arr[i]);
+ 
+    // Traverse through all holes one by one. For
+    // every hole, take its elements and put in
+    // array.
+    int index = 0;  // index in sorted array
+    for (int i = 0; i < range; i++)
+    {
+       vector<int>::iterator it;
+       for (it = holes[i].begin(); it != holes[i].end(); ++it)
+            arr[index++]  = *it;
+    }
+}
+ 
+// Driver program to test the above function
+int main()
+{
+    int arr[] = {8, 3, 2, 7, 4, 6, 8};
+    int n = sizeof(arr)/sizeof(arr[0]);
+ 
+    pigeonholeSort(arr, n);
+ 
+    printf("Sorted order is : ");
+    for (int i = 0; i < n; i++)
+        printf("%d ", arr[i]);
+ 
+    return 0;
+}