Merge pull request knaxus#78 from gabrielbarker/jumpSearch

Add jumpSearch and Tests

Author: TheSTL

src/_Searching_/JumpSearch/JumpSearch.test.js

@@ -0,0 +1,20 @@
+const { jumpSearch, jumpSearchRecursive } = require('.');
+
+describe('Jump Search', () => {
+    const array = [1, 2, 3, 4, 5, 6, 7, 8];
+    describe('When element to find is at 1st position ', () => {
+        it('Jump search', () => {
+          expect(jumpSearch(array, 1)).toEqual(0);
+        });
+      });
+    describe('When element to find is at last position ', () => {
+        it('Jump search', () => {
+          expect(jumpSearch(array, 7)).toEqual(6);
+        });
+      });
+    describe('When element to find is at random position ', () => {
+        it('Jump search', () => {
+          expect(jumpSearch(array, 3)).toEqual(2);
+        });
+      });
+});

src/_Searching_/JumpSearch/index.js

@@ -0,0 +1,38 @@
+/**
+ * Note: Array must be sorted for jump search
+ * Complexity: 
+ * Worst case time complexity: O(√N)
+ * Average case time complexity: O(√N)
+ * Best case time complexity: O(1)
+ * Space complexity: O(1)
+*/
+function jumpSearch(arr, key) {
+    const n = arr.length;
+    const jump = Math.floor(Math.sqrt(n));
+    let step = jump;
+
+    let prev = 0;
+    
+    while(arr[Math.min(step, n) - 1] < key) {
+        prev = step;
+        step += jump;
+        if (prev >= n) 
+            return null; 
+    }
+
+    while(arr[prev] < key) {
+        prev++;
+
+        if (prev == Math.min(step, n))
+            return null;
+    }
+    
+    if (arr[prev] == key) 
+        return prev; 
+
+    return null;
+  }
+  
+  module.exports = {
+    jumpSearch,
+  };