From 5309dc7151411afc4f85125ca5c9ed47f55452be Mon Sep 17 00:00:00 2001
From: openset <openset.wang@gmail.com>
Date: Thu, 30 May 2019 14:47:41 +0800
Subject: [PATCH] Add: Last Stone Weight

---
 .../last-stone-weight/last_stone_weight.go    | 19 ++++++++++++
 .../last_stone_weight_test.go                 | 31 +++++++++++++++++++
 2 files changed, 50 insertions(+)
 create mode 100644 problems/last-stone-weight/last_stone_weight.go
 create mode 100644 problems/last-stone-weight/last_stone_weight_test.go

diff --git a/problems/last-stone-weight/last_stone_weight.go b/problems/last-stone-weight/last_stone_weight.go
new file mode 100644
index 000000000..b1ad42f22
--- /dev/null
+++ b/problems/last-stone-weight/last_stone_weight.go
@@ -0,0 +1,19 @@
+package last_stone_weight
+
+import "sort"
+
+func lastStoneWeight(stones []int) int {
+	for len(stones) >= 2 {
+		n := len(stones) - 1
+		sort.Ints(stones)
+		v := stones[n] - stones[n-1]
+		if v > 0 {
+			stones[n-1] = v
+		} else {
+			n--
+		}
+		stones = stones[:n]
+	}
+	stones = append(stones, 0)
+	return stones[0]
+}
diff --git a/problems/last-stone-weight/last_stone_weight_test.go b/problems/last-stone-weight/last_stone_weight_test.go
new file mode 100644
index 000000000..4b812dc5b
--- /dev/null
+++ b/problems/last-stone-weight/last_stone_weight_test.go
@@ -0,0 +1,31 @@
+package last_stone_weight
+
+import "testing"
+
+type caseType struct {
+	input    []int
+	expected int
+}
+
+func TestLastStoneWeight(t *testing.T) {
+	tests := [...]caseType{
+		{
+			input:    []int{2, 7, 4, 1, 8, 1},
+			expected: 1,
+		},
+		{
+			input:    []int{2, 7, 4, 1, 8, 1, 5},
+			expected: 0,
+		},
+		{
+			input:    []int{316, 157, 73, 106, 771, 828},
+			expected: 37,
+		},
+	}
+	for _, tc := range tests {
+		output := lastStoneWeight(tc.input)
+		if output != tc.expected {
+			t.Fatalf("input: %v, output: %v, expected: %v", tc.input, output, tc.expected)
+		}
+	}
+}