Add input validation to coin change algorithms

Author: MayankSharma-2812

Dynamic-Programming/CoinChange.js

@@ -3,24 +3,57 @@
  * @params {Number} amount
  */
 export const change = (coins, amount) => {
-  // Create and initialize the storage
+  if (!Array.isArray(coins)) {
+    throw new TypeError('Coins must be an array')
+  }
+
+  if (typeof amount !== 'number' || amount < 0) {
+    throw new TypeError('Amount must be a non-negative number')
+  }
+
+  if (amount === 0) {
+    return 1
+  }
+
+  if (coins.length === 0) {
+    return 0
+  }
+
   const combinations = new Array(amount + 1).fill(0)
   combinations[0] = 1
-  // Determine the direction of smallest sub-problem
+
   for (let i = 0; i < coins.length; i++) {
-    // Travel and fill the combinations array
     for (let j = coins[i]; j < combinations.length; j++) {
       combinations[j] += combinations[j - coins[i]]
     }
   }
+
   return combinations[amount]
 }
+
 /**
  * @params {Array} coins
  * @params {Number} amount
  */
 export const coinChangeMin = (coins, amount) => {
-  const map = { 0: 1 }
+  if (!Array.isArray(coins)) {
+    throw new TypeError('Coins must be an array')
+  }
+
+  if (typeof amount !== 'number' || amount < 0) {
+    throw new TypeError('Amount must be a non-negative number')
+  }
+
+  if (amount === 0) {
+    return 0
+  }
+
+  if (coins.length === 0) {
+    return -1
+  }
+
+  const map = { 0: 0 }
+
   for (let i = 1; i <= amount; i++) {
     let min = Infinity
     for (const coin of coins) {
@@ -29,5 +62,6 @@ export const coinChangeMin = (coins, amount) => {
     }
     map[i] = min
   }
-  return map[amount] === Infinity ? -1 : map[amount] - 1
+
+  return map[amount] === Infinity ? -1 : map[amount]
 }