chore(C): added Interpolation Search (#337)

algorithms/C/README.md

@@ -34,3 +34,4 @@
 - [Binary Search](searching/Binary-search.c)
 - [Jump Search](searching/Jump-search.c)
 - [Ternary Search](searching/Ternary-search.c)
+- [Interpolation Search](searching/Interpolation-search.c)

algorithms/C/searching/Interpolation-search.c

@@ -0,0 +1,72 @@
+/*
+Program to search data in array using interpolation search
+Interpolation search: Used to search data in a sequence stored array
+*/
+
+#include <stdio.h>
+
+#include <stdlib.h>
+ // Function to search data in a given array
+int interpolation_search(int * arr, int low, int high, int to_search) {
+  if (low <= high && to_search >= arr[low]) {
+        if(arr[high]==arr[low]&&to_search==arr[high]&&arr[low]==to_search)
+        return high;
+    // formula to find index
+    int pos = low + (to_search - arr[low]) * (high - low) / (arr[high] - arr[low]);
+
+    // if data found
+    if (arr[pos] == to_search)
+      return pos;
+    // if data is less than current position
+    else if (arr[pos] > to_search)
+      high = pos - 1;
+    // if data is greater than the current position
+    else if (arr[pos] < to_search)
+      low = pos + 1;
+    // recursive call
+    return interpolation_search(arr, low, high, to_search);
+  }
+  // return -1 if the if condition fails
+  return -1;
+}
+//driver code
+int main() {
+  int * arr, size, index, to_search, i;
+
+  printf("Enter the size: ");
+  // taking size
+  scanf("%d", & size);
+  // dynamically locating memory
+  arr = (int * ) malloc(sizeof(int) * size);
+    if(arr==NULL)
+    {
+        printf("Memory not allocated Please try again");
+        exit(0);
+    }
+  for (i = 0; i < size; i++) {
+    scanf("%d", & arr[i]);
+  }
+  printf("Enter the number to search: ");
+  // taking the number to search
+  scanf("%d", & to_search);
+  // calling interpolation search
+  index = interpolation_search(arr, 0, size - 1, to_search);
+  // If element was found
+  if (index != -1)
+    printf("Element found at index number: %d", index);
+  // If element was not found
+  else
+    printf("Element not found");
+
+  return 0;
+}
+/*
+Input: Enter the size: 5
+10 20 30 40 50
+Enter the data to search: 40
+Output: Element found at index number: 3
+
+Time complexity: O(log2(log2 n))
+Space Complexity: O(1)
+
+*/