Playlist Runtime

A type Song struct { Title string; Seconds int } groups related data into one value, and func (s Song) Format() string attaches behavior to it — inside the method, s refers to whichever Song value it was called on, so song.Format() runs the method with s bound to song. Splitting a duration into minutes and seconds is a classic use of two operators together: / gives you the whole minutes, and % (modulo) gives you whatever's left over that doesn't make a full minute.

Worked example

Here's the same Song struct and method used on a two-song playlist:

package main

import "fmt"

type Song struct {
	Title   string
	Seconds int
}

func (s Song) Format() string {
	minutes := s.Seconds / 60
	seconds := s.Seconds % 60
	return fmt.Sprintf("%d:%02d", minutes, seconds)
}

func main() {
	playlist := []Song{
		{"Rainy Day", 125},
		{"Night Drive", 305},
	}

	totalSeconds := 0
	fmt.Println("Playlist:")
	for i := 0; i < len(playlist); i++ {
		song := playlist[i]
		fmt.Printf("%s - %s\n", song.Title, song.Format())
		totalSeconds = totalSeconds + song.Seconds
	}

	fmt.Printf("Total runtime: %d:%02d\n", totalSeconds/60, totalSeconds%60)
}

Playlist:
Rainy Day - 2:05
Night Drive - 5:05
Total runtime: 7:10

Each song's Format() call turns its raw second count into a clean minutes:seconds string, and the loop keeps a running total across all of them.

Your turn

The starter program's Format method computes minutes correctly but reuses the wrong operator for seconds, and the loop in main is meant to build up a running total but shrinks it instead. Fix both marked lines.

If something goes wrong

If every song's seconds display matches its minutes (like "3:3" instead of "3:35"), you're still dividing twice instead of using % for the second value. If the total runtime prints as a negative-looking or oddly small time, check that the accumulator line adds each song's seconds rather than subtracting them. With this playlist's three songs (215, 187, and 260 seconds), the total is 662 seconds — 11 whole minutes and 2 leftover seconds — so a total that doesn't match that means one of the two fixes is still missing.