Notification: This article are some useful snippets for OnlineJudge, especially for Leetcode.

1. sort int slice

	sort.Slice(nums, func(i, j int) bool {
		return nums[i] < nums[j]
	})

1. sort struct

	sort.Slice(people, func(i, j int) bool {
		return people[i].age < people[j].age
	})

1. int heap ```go type IntHeap []int

// h.Len() func (h IntHeap) Len() int { return len(h) } func (h IntHeap) Less(i, j int) bool { return h[i] < h[j] } func (h IntHeap) Swap(i, j int) { h[i], h[j] = h[j], h[i] } func (h IntHeap) Peek() int { return (h)[0] }

// heap.Push(h, val) func (h IntHeap) Push(x interface{}) { *h = append(h, x.(int)) }

func (h *IntHeap) Pop() interface{} { old := *h n := len(old) x := old[n-1] *h = old[0 : n-1] return x }

## String
[doc](https://golang.org/pkg/strings/?m=all)

1. reverse
```go
func Reverse(s string) string {
	r := []rune(s)
	for i, j := 0, len(r)-1; i < len(r)/2; i, j = i+1, j-1 {
		r[i], r[j] = r[j], r[i]
	}
	return string(r)
}

1. swap string

   func swap(str1, str2 *string) {
    *str1, *str2 = *str2, *str1
   }
   func main() {
    a := "salut"
    b := "les gens"
    swap(&a, &b)
    fmt.Printf("a=%s\nb=%s\n", a, b)
   }
   

2. empty string

   var s string
   fmt.Println(s=="") // prints "true"
   

slice

1. Add a element at the first

   data := []string{"A", "B", "C", "D"}
   data = append([]string{"Prepend Item"}, data...)
   fmt.Println(data)
   // [Prepend Item A B C D]
   

2. push back

stack

// A unsafe thread !

type stack []int

func (s stack) Push(v int) stack {
    return append(s, v)
}

func (s stack) Pop() (stack, int) {
    l := len(s)
    return  s[:l-1], s[l-1]
}

func main(){
    s := make(stack,0)
    s = s.Push(1)
    s = s.Push(2)
    s = s.Push(3)

    s, p := s.Pop()
    fmt.Println(p)
}

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