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Go Quick Start

Basic Syntax

The Go Programming Language (Chinese)

Common Libraries

Slices

Go simulates stacks and queues using slices.

Stack

// Create a stack
stack:=make([]int,0)
// push
stack=append(stack,10)
// pop
v:=stack[len(stack)-1]
stack=stack[:len(stack)-1]
// Check if the stack is empty
len(stack)==0

Queue

// Create a queue
queue:=make([]int,0)
// enqueue
queue=append(queue,10)
// dequeue
v:=queue[0]
queue=queue[1:]
// A length of 0 means empty
len(queue)==0

Things to note

  • When passing as a parameter, you can only modify the data; you cannot add to or delete from the original data.
  • By default s=s[0:len(s)], which includes the lower bound but excludes the upper bound, mathematically expressed as: [)

Maps

Basic usage

// Create
m:=make(map[string]int)
// Set a key-value pair
m["hello"]=1
// Delete a key
delete(m,"hello")
// Iterate
for k,v:=range m{
    println(k,v)
}

Things to note

  • Map keys must be comparable; they cannot be a slice, map, or function.
  • Map values always have a default value, which you can operate on directly, e.g. m[age]++ changes the value from 0 to 1.
  • Comparing two maps requires iterating to check whether their key-value pairs are the same. Because of the default-value behavior, you need to check both the val and ok values.

Standard Library

sort

// Sort ints
sort.Ints([]int{})
// Sort strings
sort.Strings([]string{})
// Custom sort
sort.Slice(s,func(i,j int)bool{return s[i]<s[j]})

math

// int32 max and min values
math.MaxInt32 // Actual value: 1<<31-1
math.MinInt32 // Actual value: -1<<31
// int64 max and min values (int defaults to int64)
math.MaxInt64
math.MinInt64

copy

// To delete a[i], use copy to overwrite position i with values from i+1 to the end, then shrink by 1
copy(a[i:],a[i+1:])
a=a[:len(a)-1]

// If make creates a length, assign by index
a:=make([]int,n)
a[n]=x
// If make has length 0, assign using append()
a:=make([]int,0)
a=append(a,x)

Common Tricks

Type conversion

// byte to number
s="12345"  // s[0] is of type byte
num:=int(s[0]-'0') // 1
str:=string(s[0]) // "1"
b:=byte(num+'0') // '1'
fmt.Printf("%d%s%c\n", num, str, b) // 111

// string to number
num,_:=strconv.Atoi()
str:=strconv.Itoa()

Notes for Solving Problems

  • On LeetCode, do not use a global variable as a return value, otherwise the problem checker will report an error.