Loops: Range over Map

Maps are key-value pairs, and range provides a convenient way to iterate over all the entries in a map. Unlike slices, when you range over a map, you get the key and value for each entry.

Basic Map Iteration

When you use range with a map, it returns two values on each iteration: the key and the value.

ages := map[string]int{
    "Goku": 30,
    "Vegeta": 35,
    "Gohan": 20,
}

for name, age := range ages {
    fmt.Println(name, "is", age, "years old")
}
// Output (order may vary):
// Goku is 30 years old
// Vegeta is 35 years old
// Gohan is 20 years old

The first variable receives the key, and the second receives the value associated with that key.

Important: Map Iteration Order is Random

Unlike slices, maps in Go do not maintain any order. Each time you iterate over a map, the entries may appear in a different order:

powerLevels := map[string]int{
    "Goku": 9000,
    "Vegeta": 8500,
    "Gohan": 8000,
}

// First iteration might print:
// Vegeta: 8500
// Gohan: 8000
// Goku: 9000

// Second iteration might print:
// Goku: 9000
// Vegeta: 8500
// Gohan: 8000

This is intentional - Go randomizes map iteration order to prevent developers from relying on it. If you need a specific order, you must sort the keys yourself.

Using Just the Keys

You can ignore the values by using the blank identifier _:

capitals := map[string]string{
    "USA": "Washington D.C.",
    "Japan": "Tokyo",
    "France": "Paris",
}

for country := range capitals {
    fmt.Println(country)
}
// Prints just the keys (order may vary):
// USA
// Japan
// France

Or simply omit the second variable:

for country := range capitals {
    fmt.Println("Country:", country)
}

Using Just the Values

To iterate over just the values, you need to use the blank identifier for the key:

scores := map[string]int{
    "Alice": 95,
    "Bob": 87,
    "Carol": 92,
}

for _, score := range scores {
    fmt.Println("Score:", score)
}
// Prints just the values (order may vary):
// Score: 95
// Score: 87
// Score: 92

Checking and Modifying Maps

You can use the keys to modify values in the map:

inventory := map[string]int{
    "apples": 10,
    "bananas": 5,
    "oranges": 8,
}

for item, quantity := range inventory {
    if quantity < 7 {
        inventory[item] = quantity + 10  // Restock
        fmt.Println("Restocked", item)
    }
}

Empty Maps

Ranging over an empty map is safe - the loop simply won't execute:

empty := map[string]int{}

for key, value := range empty {
    fmt.Println(key, value)  // Never executes
}

fmt.Println("Done!")  // This runs normally

Assignment

For this challenge, create a function called findStrongest that accepts a parameter powerLevels (a map with string keys and int values: map[string]int).

The function should:

• Use range to iterate over the map
• Find the character with the highest power level
• Print the name of the strongest character and their power level in the format: "[name] is the strongest with [powerLevel]"

The function signature is:

func findStrongest(powerLevels map[string]int) {
    // Your code here
}

For example, calling findStrongest(map[string]int{"Goku": 9001, "Vegeta": 8500, "Gohan": 8000}) should print:

Goku is the strongest with 9001