數據結構與算法（二）數組與鏈表編程實踐

1.支持動態擴容的數組

public class DynamicArray {
        //擴容因子
        final float factor = 0.75f;
        int size = 16;
        int currentIndex = 0;
        int[] arrays = new int[size];


        private void put(int num) {
            
            if (currentIndex > size * factor) {
                //擴容並轉移數據
                int newSize = size * 2;
                size = newSize;
                int[] newArray = new int[newSize];
                for (int i = 0; i < currentIndex; i++) {
                    newArray[i] = arrays[i];
                }
//            也可以用下面的方法來做數組拷貝
//            if (currentIndex >= 0)
//                System.arraycopy(arrays, 0, newArray, 0, currentIndex);
                arrays = newArray;
            }
            arrays[currentIndex] = num;
            currentIndex++;

//            for (int i = 0; i < currentIndex; i++) {
//                System.out.print("num=" + num + "  current=" + arrays[i] + "\n");
//            }
//            System.out.println("   ");
        }

        private int get(int index){
            return arrays[index];
        }
    }

測試代碼：

  @Test
    public void Test() {
        DynamicArray dynamicArray = new DynamicArray();
        for (int i = 0; i < 100; i++) {
            dynamicArray.put(i);
        }

        System.out.println(" 下標88的值是 "+dynamicArray.get(88));
    }