LeetCode/go/rotting-oranges.go

package main

import (
	aq "github.com/emirpasic/gods/v2/queues/arrayqueue"
)

const (
	EMPTY_CELL    int = 0
	FRESH_ORANGE  int = 1
	ROTTEN_ORANGE int = 2
)

type BFSEntry struct {
	time int
	y, x int
}

func orangesRotting(grid [][]int) int {
	DIRECTIONS := [][]int{
		[]int{0, 1},
		[]int{0, -1},
		[]int{1, 0},
		[]int{-1, 0},
	}

	inBounds := func(y, x int) bool {
		return y >= 0 && y < len(grid) && x >= 0 && x < len(grid[y])
	}
	countFresh := func() int {
		fresh := 0

		for _, row := range grid {
			for _, orange := range row {
				if orange == FRESH_ORANGE {
					fresh++
				}
			}
		}

		return fresh
	}
	initializeQueue := func(q *aq.Queue[BFSEntry]) {
		for y, row := range grid {
			for x, orange := range row {
				if orange != ROTTEN_ORANGE {
					continue
				}

				q.Enqueue(BFSEntry{time: 0, y: y, x: x})
			}
		}
	}

	q := aq.New[BFSEntry]()
	initializeQueue(q)

	fresh, time := countFresh(), 0
	for !q.Empty() && fresh > 0 {
		value, _ := q.Dequeue()

		for _, d := range DIRECTIONS {
			ny, nx := value.y+d[0], value.x+d[1]
			if !inBounds(ny, nx) || grid[ny][nx] != FRESH_ORANGE {
				continue
			}

			grid[ny][nx] = ROTTEN_ORANGE
			fresh--
			q.Enqueue(BFSEntry{time: value.time + 1, y: ny, x: nx})
			time = value.time + 1
		}
	}

	if fresh > 0 {
		return -1
	}

	return time
}