Merge pull request #301 from ihsg/kotlin

[kotlin版本] 动态扩容数组

Author: wangzheng0822

kotlin/05_array/DynamicArray.kt

@@ -0,0 +1,118 @@
+/**
+ * 动态扩容的数组
+ */
+class DynamicArray {
+    companion object {
+        // 默认容量
+        const val DEFAULT_CAPACITY = 10
+
+        // 最大容量
+        const val MAX_CAPACITY = Int.MAX_VALUE
+    }
+
+    // 当前已使用大小
+    private var usedSize = 0
+
+    // 当前容量大小
+    private var capacity = 0
+
+    // 数组容器
+    private var data: Array<Int>
+
+    init {
+        this.capacity = DEFAULT_CAPACITY
+        this.data = Array(this.capacity) { 0 }
+    }
+
+    /**
+     * 增加元素
+     */
+    fun add(value: Int) {
+        if (this.usedSize == this.capacity - 1) {
+            this.doubleCapacity()
+        }
+        this.data[this.usedSize] = value
+        ++this.usedSize
+    }
+
+    /**
+     * 移除元素
+     */
+    fun remove(value: Int) {
+        if (this.usedSize >= 0) {
+            var target = -1
+
+            // 查找目标所在位置
+            for (i in 0 until this.usedSize) {
+                if (this.data[i] == value) {
+                    target = i
+                    break
+                }
+            }
+
+            // 找到了
+            if (target >= 0) {
+                val size = this.usedSize - 1
+
+                // 把后续元素往前搬
+                for (i in target until size) {
+                    this.data[i] = this.data[i + 1]
+                }
+
+                // 最后一个元素位置置为空
+                this.data[size] = 0
+
+                // 更新已使用大小
+                this.usedSize = size
+            }
+        }
+    }
+
+    /**
+     * 通过索引设置元素的值
+     */
+    fun set(index: Int, value: Int) {
+        if (this.checkIndex(index)) {
+            this.data[index] = value
+            return
+        }
+
+        throw IllegalArgumentException("index must be in rang of 0..${this.usedSize}")
+    }
+
+    /**
+     * 获取元素
+     */
+    fun get(index: Int): Int? {
+        if (this.checkIndex(index)) {
+            return this.data[index]
+        }
+
+        throw IllegalArgumentException("index must be in rang of 0..${this.usedSize}")
+    }
+
+    /**
+     * 获取当前数组的大小
+     */
+    fun getSize(): Int = this.usedSize
+
+    private fun checkIndex(index: Int): Boolean {
+        return index >= 0 && index < this.usedSize
+    }
+
+    /**
+     * 按原容量的两倍进行扩容
+     */
+    private fun doubleCapacity() {
+        if (this.capacity < MAX_CAPACITY) {
+            this.capacity = Math.min(this.capacity * 2, MAX_CAPACITY)
+            val newArray = Array(this.capacity) { 0 }
+
+            for (i in 0 until this.usedSize) {
+                newArray[i] = this.data[i]
+            }
+
+            this.data = newArray
+        }
+    }
+}