go: add «1381. Design a Stack With Increment Operation»

Signed-off-by: Matej Focko <me@mfocko.xyz>

go/design-a-stack-with-increment-operation.go

@@ -0,0 +1,39 @@
+package main
+
+type CustomStack struct {
+	maxSize int
+	stack   []int
+	size    int
+}
+
+func Constructor(maxSize int) CustomStack {
+	return CustomStack{
+		maxSize: maxSize,
+		stack:   make([]int, maxSize),
+		size:    0,
+	}
+}
+
+func (this *CustomStack) Push(x int) {
+	if this.size >= this.maxSize {
+		return
+	}
+
+	this.stack[this.size] = x
+	this.size++
+}
+
+func (this *CustomStack) Pop() int {
+	if this.size <= 0 {
+		return -1
+	}
+
+	this.size--
+	return this.stack[this.size]
+}
+
+func (this *CustomStack) Increment(k int, val int) {
+	for i := 0; i < k && i < this.size; i++ {
+		this.stack[i] += val
+	}
+}