From 21e95a3c3172396f23617a52d7016e62acf0d323 Mon Sep 17 00:00:00 2001
From: Kei Kamikawa <code-hex@users.noreply.github.com>
Date: Tue, 14 Apr 2020 21:53:25 +0900
Subject: [PATCH] added last stone weight solution

---
 last-stone-weight/solution.go      | 26 ++++++++++++++++++++++++
 last-stone-weight/solution_test.go | 32 ++++++++++++++++++++++++++++++
 2 files changed, 58 insertions(+)
 create mode 100644 last-stone-weight/solution.go
 create mode 100644 last-stone-weight/solution_test.go

diff --git a/last-stone-weight/solution.go b/last-stone-weight/solution.go
new file mode 100644
index 0000000..de09874
--- /dev/null
+++ b/last-stone-weight/solution.go
@@ -0,0 +1,26 @@
+package solution
+
+import "sort"
+
+// Last Stone Weight
+// https://leetcode.com/explore/challenge/card/30-day-leetcoding-challenge/529/week-2/3297/
+
+// Note:
+//
+// 1 <= stones.length <= 30
+// 1 <= stones[i] <= 1000
+func lastStoneWeight(stones []int) int {
+	for {
+		sort.Ints(stones)
+		ln := len(stones)
+		switch ln {
+		case 0:
+			return 0
+		case 1:
+			return stones[0]
+		}
+
+		diff := stones[ln-1] - stones[ln-2]
+		stones = append(stones[:ln-2], diff)
+	}
+}
diff --git a/last-stone-weight/solution_test.go b/last-stone-weight/solution_test.go
new file mode 100644
index 0000000..be67ce2
--- /dev/null
+++ b/last-stone-weight/solution_test.go
@@ -0,0 +1,32 @@
+package solution
+
+import (
+	"fmt"
+	"testing"
+)
+
+func Test_lastStoneWeight(t *testing.T) {
+	type args struct {
+	}
+	tests := []struct {
+		stones []int
+		want   int
+	}{
+		{
+			stones: []int{2, 7, 4, 1, 8, 1},
+			want:   1,
+		},
+		{
+			stones: []int{2, 7, 4, 1, 8, 1, 3, 4, 100, 304, 1000},
+			want:   566,
+		},
+	}
+	for i, tt := range tests {
+		title := fmt.Sprintf("testcase: %d", i+1)
+		t.Run(title, func(t *testing.T) {
+			if got := lastStoneWeight(tt.stones); got != tt.want {
+				t.Errorf("lastStoneWeight() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}