Problem: Number of Islands

main.go

// Problem: https://leetcode.com/problems/number-of-islands/
// ASCII byte reference
// 48  = "0"
// 49  = "1"
// 120 = "x"
package main

import "fmt"

func findBounds(input [][]byte, row, col int) int {
	if row < 0 || row >= len(input) {
		return 0
	} else if col < 0 || col >= len(input[row]) {
		return 0
	} else if input[row][col] != 49 {
		return 0
	}

	var contiguous int = 1
	input[row][col] = 120
	contiguous += findBounds(input, row+1, col)
	contiguous += findBounds(input, row-1, col)
	contiguous += findBounds(input, row, col+1)
	contiguous += findBounds(input, row, col-1)
	return contiguous
}

func numIslands(input [][]byte) int {
	var islands int
	for row := range input {
		for col := range input[row] {
			if input[row][col] != 49 {
				continue
			}
			// Once land is encountered, mark all contiguous blocks with an "x"
			findBounds(input, row, col)
			islands++
		}
	}
	return islands
}
func main() {
	// Leetcode gives the input is a 2d byte slice so
	// using the ASCII values for '0', '1', and 'x'
	var input = [][]byte{
		{49, 49, 48, 48, 48},
		{49, 49, 48, 48, 48},
		{48, 48, 49, 48, 48},
		{48, 48, 48, 49, 49},
	}
	count := numIslands(input)
	fmt.Printf("Islands: %d\n", count)
}

$ go run main.go
Islands: 3