diff --git a/20201226/main.go b/20201226/main.go
new file mode 100644
index 0000000..3c7b887
--- /dev/null
+++ b/20201226/main.go
@@ -0,0 +1,54 @@
+package main
+
+import (
+	"math"
+	"sort"
+)
+
+func main() {
+
+}
+
+func findThirdMax(nums []int) int {
+	if len(nums) == 0 {
+		return 0
+	}
+	sort.Sort(sort.Reverse(sort.IntSlice(nums)))
+	if len(nums) < 3 {
+		return nums[0]
+	}
+	v := nums[0]
+	count := 0
+	for _, n := range nums {
+		v = n
+		if count == 3 {
+			break
+		}
+		if v > n {
+			count++
+		}
+	}
+	return v
+}
+
+func findThirdMax2(nums []int) int {
+	vs := [3]int{math.MinInt64, math.MinInt64, math.MinInt64}
+	found := false
+	for _, n := range nums {
+		if n == vs[0] || n == vs[1] || n == vs[2] {
+			continue
+		}
+		if n > vs[0] {
+			vs[0], vs[1], vs[2] = n, vs[0], vs[1]
+		} else if n > vs[1] {
+			vs[1], vs[2] = n, vs[1]
+		} else if n > vs[2] {
+			found = true
+			vs[2] = n
+		}
+	}
+	if found {
+		return vs[2]
+	}
+	return vs[0]
+}
diff --git a/20201226/main_test.go b/20201226/main_test.go
new file mode 100644
index 0000000..320ab96
--- /dev/null
+++ b/20201226/main_test.go
@@ -0,0 +1,90 @@
+package main
+
+import "testing"
+
+func Test_findThirdMax(t *testing.T) {
+	type args struct {
+		nums []int
+	}
+	tests := []struct {
+		name string
+		args args
+		want int
+	}{
+		{
+			"in:[3,2,1],out:1",
+			args{
+				[]int{3, 2, 1},
+			},
+			1,
+		},
+		{
+			"in:[1,2],out:2",
+			args{
+				[]int{1, 2},
+			},
+			2,
+		},
+		{
+			"in:[2,2,3,1],out:1",
+			args{
+				[]int{2, 2, 3, 1},
+			},
+			1,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := findThirdMax(tt.args.nums); got != tt.want {
+				t.Errorf("findThirdMax() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
+
+func Test_findThirdMax2(t *testing.T) {
+	type args struct {
+		nums []int
+	}
+	tests := []struct {
+		name string
+		args args
+		want int
+	}{
+		{
+			"in:[3,2,1],out:1",
+			args{
+				[]int{3, 2, 1},
+			},
+			1,
+		},
+		{
+			"in:[1,2],out:2",
+			args{
+				[]int{1, 2},
+			},
+			2,
+		},
+		{
+			"in:[2,2,3,1],out:1",
+			args{
+				[]int{2, 2, 3, 1},
+			},
+			1,
+		},
+		{
+			"in:[2,2,3],out:3",
+			args{
+				[]int{2, 2, 3},
+			},
+			3,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := findThirdMax2(tt.args.nums); got != tt.want {
+				t.Errorf("findThirdMax() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}