feat: Implement change foreign currency

  - Facebook prep

Author: brianr482

recursion/change-foreign-currency.js

@@ -0,0 +1,32 @@
+/**
+ * Facebook prep: Change in a Foreign Currency
+ * Given a list of the available denominations, determine if it's possible to
+ * receive exact change for an amount of money targetMoney. Both the
+ * denominations and target amount will be given in generic units of that
+ * currency.
+ * 
+ * Constraints:
+ * 1. 1 <= |denominations| <= 100
+ * 2. 1 <= denominations[i] <= 10000
+ * 3. 1 <= targetMoney <= 1000000
+ */
+
+ /**
+  * 
+  * @param {number} targetMoney - The target money to check if there's an exact change for
+  * @param {number[]} denominations - All possible denomination changes sorted in ascending order
+  */
+function canGetExactChange(targetMoney, denominations) {
+  for (let i = 0; i < denominations.length; i++) {
+    const denomination = denominations[i];
+    if (targetMoney < denomination) {
+      return false;
+    }
+    
+    const remaining = targetMoney % denomination;
+    if (remaining === 0 || canGetExactChange(remaining, denominations)) {
+      return true;
+    }
+  }
+  return false;
+}