From 4402f8a02c5bac3646febce6af79b213c07677c2 Mon Sep 17 00:00:00 2001
From: IcarusTheFly <IcarusTheFly@users.noreply.github.com>
Date: Sat, 14 Oct 2023 20:28:31 +1100
Subject: [PATCH 1/2] Add Interpolation search

---
 search/interpolation_search.ts           | 49 ++++++++++++++++++++++++
 search/test/interpolation_search.test.ts | 15 ++++++++
 2 files changed, 64 insertions(+)
 create mode 100644 search/interpolation_search.ts
 create mode 100644 search/test/interpolation_search.test.ts

diff --git a/search/interpolation_search.ts b/search/interpolation_search.ts
new file mode 100644
index 00000000..61942782
--- /dev/null
+++ b/search/interpolation_search.ts
@@ -0,0 +1,49 @@
+/**
+ * @function interpolationSearch
+ * @description Interpolation search is an algorithm for searching for a
+ *  key in an array that has been ordered by numerical values assigned
+ *  to the keys (key values)
+ * @param {number[]} array - list of numbers
+ * @param {number} target - target number to search for
+ * @return {number} - index of the target number in the list, or -1 if not found
+ * @see https://en.wikipedia.org/wiki/Interpolation_search
+ * @example interpolationSearch([1, 3, 5, 7, 9, 11], 1) => 0
+ */
+export const interpolationSearch = (array: number[], target: number): number => {
+  let lowIndex: number = 0;
+  let highIndex: number = array.length - 1;
+  let currentValue: number = array[lowIndex];
+  let pos: number = 0;
+
+  while (lowIndex <= highIndex) {
+    const lowValue: number = array[lowIndex];
+    const highValue: number = array[highIndex];
+
+    if (lowValue === highValue) {
+      if (array[lowIndex] === target) {
+        return lowIndex;
+      }
+      break;
+    }
+
+    pos = Math.round(lowIndex + (target-lowValue)*(highIndex-lowIndex) / (highValue-lowValue));
+
+    if (pos < 0 || pos >= array.length) {
+      break;
+    }
+
+    currentValue = array[pos];
+
+    if (target === currentValue) {
+      return pos;
+    }
+
+    if (target > currentValue) {
+      lowIndex = pos + 1;
+    } else {
+      highIndex = pos - 1;
+    }
+  }
+
+  return -1;
+}
\ No newline at end of file
diff --git a/search/test/interpolation_search.test.ts b/search/test/interpolation_search.test.ts
new file mode 100644
index 00000000..6cc6e4e2
--- /dev/null
+++ b/search/test/interpolation_search.test.ts
@@ -0,0 +1,15 @@
+import { interpolationSearch } from "../interpolation_search";
+
+describe("Interpolation search", () => {
+  test.each([
+    [[1, 3, 5, 7, 9, 11], 1, 0],
+    [[1, 3, 7, 10, 14, 15, 16, 18, 20, 21, 22, 23, 25, 33, 35, 42, 45, 47, 50, 52], 33, 13],
+    [[0, 45, 67, 70, 89, 129, 150, 308], 308, 7],
+    [[0, 45, 67, 70, 89, 129, 150, 308], 190, -1]
+  ])(
+    "of %o, searching for %o, expected %i",
+    (array: any[], target: any, index: number) => {
+      expect(interpolationSearch(array, target)).toStrictEqual(index)
+    },
+  );
+});

From 41b2ca0cbb3518c15e3d6ecdac5a9bf05525d250 Mon Sep 17 00:00:00 2001
From: IcarusTheFly <IcarusTheFly@users.noreply.github.com>
Date: Sat, 14 Oct 2023 20:35:47 +1100
Subject: [PATCH 2/2] Add new algorithm to directory

---
 DIRECTORY.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/DIRECTORY.md b/DIRECTORY.md
index ce0e7c51..166aea22 100644
--- a/DIRECTORY.md
+++ b/DIRECTORY.md
@@ -110,6 +110,7 @@
 
 ## Search
   * [Binary Search](https://github.com/TheAlgorithms/TypeScript/blob/HEAD/search/binary_search.ts)
+  * [Interpolation Search](https://github.com/TheAlgorithms/TypeScript/blob/HEAD/search/interpolation_search.ts)
   * [Jump Search](https://github.com/TheAlgorithms/TypeScript/blob/HEAD/search/jump_search.ts)
   * [Linear Search](https://github.com/TheAlgorithms/TypeScript/blob/HEAD/search/linear_search.ts)