Coin Change Minimum Coins in DSA Typescript - Build from Scratch

Coin Change Minimum Coins

📖 Scenario: You are helping a cashier machine that needs to give change using the fewest coins possible. The machine has coins of certain values, and you want to find the minimum number of coins needed to make a specific amount.

🎯 Goal: Build a program that finds the minimum number of coins needed to make a given amount using a list of coin values.

📋 What You'll Learn

Create an array called coins with the values 1, 5, and 10

Create a variable called amount and set it to 12

Write a function called minCoins that takes coins and amount and returns the minimum number of coins needed

Print the result of calling minCoins(coins, amount)

💡 Why This Matters

🌍 Real World

Cashier machines, vending machines, and payment apps use this logic to give change efficiently.

💼 Career

Understanding dynamic programming and optimization problems is useful for software engineers working on finance, retail, or algorithmic challenges.

1

Create the coins array

Create an array called coins with the values 1, 5, and 10.

DSA Typescript

# Your code here

Hint

Use square brackets to create an array and separate values with commas.

2

Set the amount variable

Create a variable called amount and set it to 12.

DSA Typescript

const coins = [1, 5, 10];
# Your code here

Hint

Use const to create a variable that does not change.

3

Write the minCoins function

Write a function called minCoins that takes coins and amount as parameters and returns the minimum number of coins needed to make the amount. Use a simple dynamic programming approach with an array called dp where dp[i] stores the minimum coins for amount i. Initialize dp[0] to 0 and others to a large number. Use a for loop with variable i from 1 to amount, and inside it, a for loop with variable coin over coins to update dp[i].

DSA Typescript

const coins = [1, 5, 10];
const amount = 12;

# Your code here

Hint

Use two loops: one for amounts from 1 to amount, and one for each coin. Update dp[i] with the minimum coins needed.

4

Print the minimum coins needed

Print the result of calling minCoins(coins, amount).

DSA Typescript

const coins = [1, 5, 10];
const amount = 12;

function minCoins(coins: number[], amount: number): number {
    const dp: number[] = new Array(amount + 1).fill(Infinity);
    dp[0] = 0;
    for (let i = 1; i <= amount; i++) {
        for (const coin of coins) {
            if (coin <= i) {
                dp[i] = Math.min(dp[i], dp[i - coin] + 1);
            }
        }
    }
    return dp[amount] === Infinity ? -1 : dp[amount];
}

# Your code here

Hint

Use console.log(minCoins(coins, amount)) to print the result.