diff --git a/codecov/abc.go b/codecov/abc.go
new file mode 100644
index 0000000..5e8fa61
--- /dev/null
+++ b/codecov/abc.go
@@ -0,0 +1,140 @@
+//找到数组中的中位数 6 / 3 = 2
+//[10,12,15,20,30,31]
+
+package codecov
+
+import (
+	"fmt"
+	"sort"
+	"strings"
+)
+
+const (
+	a = iota
+	b
+	c
+	d
+)
+
+type st struct {
+	A string
+}
+
+func ReverseWords2(s string) string {
+	source := strings.Fields(s)
+	fmt.Println(source)
+	an := len(source)
+	am := an / 2
+	for i := 0; i < am; i++ {
+		source[i], source[an-1-i] = source[an-1-i], source[i]
+	}
+	return strings.Join(source, " ")
+}
+func ReverseWords(s string) string {
+	source := strings.Split(s, " ")
+	an := len(source)
+	am := an / 2
+	for i := 0; i < am; i++ {
+		left := reverse(source[i])
+		right := reverse(source[an-1-i])
+		source[i], source[an-1-i] = right, left
+	}
+
+	return strings.Join(source, " ")
+}
+
+func reverse(source string) string {
+	b := []rune(source) //中文
+	n := len(b)
+	mid := n / 2
+	for i := 0; i < mid; i++ {
+		b[i], b[n-1-i] = b[n-1-i], b[i]
+	}
+	return string(b)
+}
+
+func Append(ss []int) {
+	ss = append(ss, 5)
+}
+
+func boyun(arr []int) int {
+	sum := 0
+	l := len(arr)
+	if l == 0 {
+		return 0
+	}
+	if l < 2 {
+		return arr[0]
+	}
+	for _, v := range arr {
+		sum += v
+	}
+	mid := sum / l
+	fmt.Printf("sum=%d, len=%d,mid=%d", sum, l, mid)
+
+	//排序
+	sort.Ints(arr)
+
+	var result int
+	for i := 0; i < l/2; i++ {
+		//头，尾对撞，快速查找
+
+		//处理左半部分
+		left := arr[i]
+		right := arr[i+1]
+		result_left := search(left, mid, right)
+
+		//右半部分
+		right_left := arr[l-2]
+		right_right := arr[l-1]
+		result_right := search(right_left, mid, right_right)
+
+		if result_left < result_right {
+			result = result_left
+		} else {
+			result = result_right
+		}
+
+	}
+
+	return result
+}
+
+func search(left, mid, right int) (result int) {
+	if left < mid && mid < right {
+		//[10,12,15,20,30,31]
+		ll := result - left  //1
+		rr := right - result //2
+		//找到
+		if ll < rr {
+			return left
+		} else {
+			return right
+		}
+	}
+	return
+}
+
+func maxChildArr(arr []int, count int) (int, []int) {
+
+	// l := len(arr)
+	// mid := l / 2
+	if count <= 0 {
+		return 0, nil
+	}
+
+	max, begin, k := 1, 0, 1
+	for idx, _ := range arr {
+		if idx > 0 && arr[idx] > arr[idx-1] {
+			k++
+		} else {
+			k = 1
+		}
+		if k > max {
+			max = k
+
+			begin = idx - max + 1
+		}
+	}
+	return max, arr[begin : begin+max]
+}