test_lanes.go

package main

import (
	"reflect"
	"sort"
	"testing"
)

type item struct {
	from int
	to   int
	lane int
}

func arrange(it []item) []item {
	// sort first
	sort.Slice(it, func(i, j int) bool { return it[i].from < it[j].from })
Loop:
	for n := range it {
		if n == 0 {
			it[n].lane = 0
			continue
		}
		maxLane := 0
		for i := 0; i < n; i++ {
			maxLane = it[i].lane
			if it[n].from >= it[i].to {
				it[n].lane = it[i].lane
				break Loop
			}
		}
		it[n].lane = maxLane + 1
	}
	return it
}

func Test_arrange(t *testing.T) {
	tests := []struct {
		name string
		args []item
		want []item
	}{
		{
			"",
			[]item{
				item{1, 3, -1},
			},
			[]item{
				item{1, 3, 0},
			},
		},
		{
			"",
			[]item{
				item{1, 3, -1},
				item{2, 4, -1},
				item{3, 4, -1},
			},
			[]item{
				item{1, 3, 0},
				item{2, 4, 1},
				item{3, 4, 0},
			},
		},
		{
			"",
			[]item{
				item{1, 4, -1},
				item{2, 4, -1},
				item{3, 4, -1},
				item{4, 6, -1},
			},
			[]item{
				item{1, 4, 0},
				item{2, 4, 1},
				item{3, 4, 2},
				item{4, 6, 0},
			},
		},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			if got := arrange(tt.args); !reflect.DeepEqual(got, tt.want) {
				t.Errorf("arrange() = %v, want %v", got, tt.want)
			}
		})
	}
}