From f73081084c57f9e7df3bb25d389ade666d5eed29 Mon Sep 17 00:00:00 2001
From: Shuo <openset.wang@gmail.com>
Date: Tue, 7 Apr 2020 12:53:53 +0800
Subject: [PATCH] A: Find Lucky Integer in an Array

---
 .../find_lucky_integer_in_an_array.go         | 15 +++++++
 .../find_lucky_integer_in_an_array_test.go    | 39 +++++++++++++++++++
 2 files changed, 54 insertions(+)
 create mode 100644 problems/find-lucky-integer-in-an-array/find_lucky_integer_in_an_array.go
 create mode 100644 problems/find-lucky-integer-in-an-array/find_lucky_integer_in_an_array_test.go

diff --git a/problems/find-lucky-integer-in-an-array/find_lucky_integer_in_an_array.go b/problems/find-lucky-integer-in-an-array/find_lucky_integer_in_an_array.go
new file mode 100644
index 000000000..26e83d6dd
--- /dev/null
+++ b/problems/find-lucky-integer-in-an-array/find_lucky_integer_in_an_array.go
@@ -0,0 +1,15 @@
+package problem1394
+
+func findLucky(arr []int) int {
+	m := make(map[int]int)
+	for _, v := range arr {
+		m[v]++
+	}
+	ans, max := -1, 0
+	for k, v := range m {
+		if k > max && k == v {
+			ans, max = k, v
+		}
+	}
+	return ans
+}
diff --git a/problems/find-lucky-integer-in-an-array/find_lucky_integer_in_an_array_test.go b/problems/find-lucky-integer-in-an-array/find_lucky_integer_in_an_array_test.go
new file mode 100644
index 000000000..bf75d1b17
--- /dev/null
+++ b/problems/find-lucky-integer-in-an-array/find_lucky_integer_in_an_array_test.go
@@ -0,0 +1,39 @@
+package problem1394
+
+import "testing"
+
+type testType struct {
+	in   []int
+	want int
+}
+
+func TestFindLucky(t *testing.T) {
+	tests := [...]testType{
+		{
+			in:   []int{2, 2, 3, 4},
+			want: 2,
+		},
+		{
+			in:   []int{1, 2, 2, 3, 3, 3},
+			want: 3,
+		},
+		{
+			in:   []int{2, 2, 2, 3, 3},
+			want: -1,
+		},
+		{
+			in:   []int{5},
+			want: -1,
+		},
+		{
+			in:   []int{7, 7, 7, 7, 7, 7, 7},
+			want: 7,
+		},
+	}
+	for _, tt := range tests {
+		got := findLucky(tt.in)
+		if got != tt.want {
+			t.Fatalf("in: %v, got: %v, want: %v", tt.in, got, tt.want)
+		}
+	}
+}