岛屿数量

试题地址：https://leetcode-cn.com/problems/number-of-islands/

试题思路：
1、注意输入数组是字符类型、注意是岛屿的个数
2、

试题代码：

package main

import "fmt"

func main() {
    grid := [][]byte{
        {'1', '0', '1', '1', '1'},
        {'1', '0', '1', '0', '1'},
        {'1', '0', '1', '0', '1'},
        {'1', '1', '1', '0', '1'}}
    fmt.Println(numIslands(grid))
}

func numIslands(grid [][]byte) int {
    if len(grid) == 0 {
        return 0
    }
    n := len(grid)
    m := len(grid[0])
    islandnum := 0
    for i := 0; i < n; i++ {
        for j := 0; j < m; j++ {
            if grid[i][j] == '1' {
                islandDfs(i, j, n, m, grid)
                islandnum++
            }
        }
    }
    return islandnum
}

func islandDfs(i, j, n, m int, grid [][]byte) {
    if safelocation(i, j, n, m, grid) == '0' {
        return
    }
    grid[i][j] = '0'
    islandDfs(i-1, j, n, m, grid)
    islandDfs(i+1, j, n, m, grid)
    islandDfs(i, j-1, n, m, grid)
    islandDfs(i, j+1, n, m, grid)
}

func safelocation(i, j, n, m int, grid [][]byte) byte {
    if i < 0 {
        return '0'
    }
    if i >= n {
        return '0'
    }
    if j < 0 {
        return '0'
    }
    if j >= m {
        return '0'
    }
    return grid[i][j]
}