Add solution for Challenge 22 (#748)

Co-authored-by: go-interview-practice-bot[bot] <230190823+go-interview-practice-bot[bot]@users.noreply.github.com>

Author: yz4230

challenge-22/submissions/yz4230/solution-template.go

@@ -0,0 +1,67 @@
+package main
+
+import (
+	"fmt"
+)
+
+func main() {
+	// Standard U.S. coin denominations in cents
+	denominations := []int{1, 5, 10, 25, 50}
+
+	// Test amounts
+	amounts := []int{87, 42, 99, 33, 7}
+
+	for _, amount := range amounts {
+		// Find minimum number of coins
+		minCoins := MinCoins(amount, denominations)
+
+		// Find coin combination
+		coinCombo := CoinCombination(amount, denominations)
+
+		// Print results
+		fmt.Printf("Amount: %d cents\n", amount)
+		fmt.Printf("Minimum coins needed: %d\n", minCoins)
+		fmt.Printf("Coin combination: %v\n", coinCombo)
+		fmt.Println("---------------------------")
+	}
+}
+
+// MinCoins returns the minimum number of coins needed to make the given amount.
+// If the amount cannot be made with the given denominations, return -1.
+func MinCoins(amount int, denominations []int) int {
+	ret := 0
+	for i := range denominations {
+	    c := denominations[len(denominations)-i-1]
+	    ret += amount / c
+	    amount = amount % c 
+	}
+	if amount > 0 {
+	    return -1
+	}
+	return ret
+}
+
+// CoinCombination returns a map with the specific combination of coins that gives
+// the minimum number. The keys are coin denominations and values are the number of
+// coins used for each denomination.
+// If the amount cannot be made with the given denominations, return an empty map.
+func CoinCombination(amount int, denominations []int) map[int]int {
+	ret := make(map[int]int, 0)
+	for i := range denominations {
+	    c := denominations[len(denominations)-i-1]
+	    ac := amount / c
+	    if ac == 0 {
+	        continue
+	    }
+	    if retc, ok := ret[c]; ok {
+	        ret[c] = retc + ac
+	    } else {
+	        ret[c] = ac
+	    }
+	    amount = amount % c
+	}
+	if amount > 0 {
+	    return map[int]int{}
+	}
+	return ret
+}