Kotlin Program to Find Largest of Three Numbers

You can find the largest of three numbers in Kotlin using if-else statements like this: val largest = if (a >= b && a >= c) a else if (b >= a && b >= c) b else c.

Examples

Inputa=3, b=7, c=5

Output7

Inputa=10, b=10, c=2

Output10

Inputa=-1, b=-5, c=-3

Output-1

How to Think About It

To find the largest of three numbers, compare the first number with the other two using && (and) operator. If it is greater or equal to both, it is the largest. Otherwise, check the second number similarly. If neither the first nor second is largest, the third must be the largest.

Algorithm

1

Get three numbers as input: a, b, and c.

2

Check if a is greater than or equal to both b and c.

3

If yes, a is the largest number.

4

Otherwise, check if b is greater than or equal to both a and c.

5

If yes, b is the largest number.

6

Otherwise, c is the largest number.

7

Print the largest number.

Code

kotlin

fun main() {
    val a = 3
    val b = 7
    val c = 5
    val largest = if (a >= b && a >= c) a else if (b >= a && b >= c) b else c
    println("Largest number is: $largest")
}

Output

Largest number is: 7

Dry Run

Let's trace the example where a=3, b=7, c=5 through the code.

1

Compare a with b and c

Check if 3 >= 7 and 3 >= 5 → false

2

Compare b with a and c

Check if 7 >= 3 and 7 >= 5 → true

3

Assign largest

largest = 7

4

Print result

Output: Largest number is: 7

Step	Condition	Result	Largest
1	3 >= 7 && 3 >= 5	false	-
2	7 >= 3 && 7 >= 5	true	7
3	Assign largest	-	7

Why This Works

Step 1: Check first number

We use if to check if the first number is greater than or equal to the other two numbers.

Step 2: Check second number

If the first is not largest, we check if the second number is greater than or equal to the other two.

Step 3: Default to third number

If neither first nor second is largest, the third number must be the largest.

Alternative Approaches

Using maxOf function

kotlin

fun main() {
    val a = 3
    val b = 7
    val c = 5
    val largest = maxOf(a, b, c)
    println("Largest number is: $largest")
}

This uses Kotlin's built-in maxOf function for cleaner and more readable code.

Using when expression

kotlin

fun main() {
    val a = 3
    val b = 7
    val c = 5
    val largest = when {
        a >= b && a >= c -> a
        b >= a && b >= c -> b
        else -> c
    }
    println("Largest number is: $largest")
}

This uses Kotlin's when expression as an alternative to if-else for clarity.

Complexity: O(1) time, O(1) space

Time Complexity

The program performs a fixed number of comparisons (at most two), so it runs in constant time O(1).

Space Complexity

Only a few variables are used, so the space complexity is constant O(1).

Which Approach is Fastest?

All approaches run in constant time, but using maxOf is more readable and idiomatic in Kotlin.

Approach	Time	Space	Best For
If-else statements	O(1)	O(1)	Simple logic, beginner understanding
maxOf function	O(1)	O(1)	Concise and idiomatic Kotlin code
when expression	O(1)	O(1)	Clear alternative to if-else