Nested loops in Go - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of nested loops with break

What is the output of this Go program?

Go

package main
import "fmt"
func main() {
    for i := 1; i <= 3; i++ {
        for j := 1; j <= 3; j++ {
            if j == 2 {
                break
            }
            fmt.Printf("%d%d ", i, j)
        }
    }
}

A 11 12 21 22 31 32

B 11 21 31

C 11 12 13 21 22 23 31 32 33

D 12 22 32

💡 Hint

Remember that break exits the inner loop immediately.

The inner loop breaks when j == 2, so only j == 1 prints for each i. The output is 11 21 31 .

❓ Predict Output

intermediate

Counting iterations in nested loops

How many times will the print statement execute in this Go code?

Go

package main
import "fmt"
func main() {
    count := 0
    for i := 0; i < 4; i++ {
        for j := 0; j < 3; j++ {
            count++
        }
    }
    fmt.Println(count)
}

A 12

B 10

C 15

D 7

💡 Hint

Multiply the number of outer loop runs by the inner loop runs.

The outer loop runs 4 times, inner loop 3 times each. Total prints = 4 * 3 = 12.

🔧 Debug

advanced

Identify the error in nested loops

What error does this Go code produce?

Go

package main
import "fmt"
func main() {
    for i := 0; i < 3; i++ {
        for j := 0; j < 3; j++
            fmt.Println(i, j)
    }
}

A Syntax error: missing braces for inner loop

B Syntax error: missing semicolon

C No error, prints pairs of i and j

D Runtime error: index out of range

💡 Hint

Check the syntax for loops in Go.

The inner loop lacks braces { }, which are required for multiple statements or to define the loop body properly. This causes a syntax error.

❓ Predict Output

advanced

Output of nested loops with continue

What is the output of this Go program?

Go

package main
import "fmt"
func main() {
    for i := 1; i <= 2; i++ {
        for j := 1; j <= 3; j++ {
            if j == 2 {
                continue
            }
            fmt.Printf("%d%d ", i, j)
        }
    }
}

A 12 22

B 11 12 13 21 22 23

C 11 13 21 23

D 11 21

💡 Hint

continue skips the current iteration of the inner loop.

When j == 2, the loop skips printing. So only j == 1 and j == 3 print for each i.

🧠 Conceptual

expert

Number of iterations in nested loops with variable limits

Consider this Go code snippet. What is the total number of times the inner loop's print statement executes?

Go

package main
import "fmt"
func main() {
    total := 0
    for i := 1; i <= 4; i++ {
        for j := 1; j <= i; j++ {
            total++
        }
    }
    fmt.Println(total)
}

A 20

B 16

C 8

D 10

💡 Hint

Sum the counts of inner loop runs for each outer loop iteration.

The inner loop runs 1 + 2 + 3 + 4 times = 10 times total.