1.支持动态扩容的数组
public class DynamicArray {
//扩容因子
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) {
//扩容并转移数据
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来做数组拷贝
// 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];
}
}
测试代码:
@Test
public void Test() {
DynamicArray dynamicArray = new DynamicArray();
for (int i = 0; i < 100; i++) {
dynamicArray.put(i);
}
System.out.println(" 下标88的值是 "+dynamicArray.get(88));
}
2.两个有序数组合并为一个
private void arrayMerge() {
int[] a1 = new int[]{3, 3, 5, 7, 9};
int[] a2 = new int[]{2, 4, 6, 8, 10,13,16};
int[] mergeA = new int[a1.length+a2.length];
int i1 = 0, i2 = 0;
for (int i = 0; i < mergeA.length; i++) {
int temp;
if (a1[i1] < a2[i2]) {
//插入a1数组的值
temp = a1[i1];
if (i1 < a1.length - 1)
i1++;
else {
a1[i1] = Integer.MAX_VALUE;
}
} else {
temp = a2[i2];
if (i2 < a2.length - 1)
i2++;
else {
a2[i2] = Integer.MAX_VALUE;
}
}
mergeA[i] = temp;
System.out.println("数组第" + i + "个值是" + temp);
}
}
时间复杂度O(n)
3.支持增删的有序数组
class SortedArray {
int[] arrays = new int[10];
int index = 0;
int temp = -1;//标记要插入的值是否是最大值
private void insert(int des) {
if (index >= arrays.length) {
System.out.println("满啦");
return;
}
for (int i = 0; i < index; i++) {
if (des < arrays[i]) {
temp = arrays[index - 1];
for (int j = index; j > i; j--) {
arrays[j] = arrays[j - 1];
}
arrays[i] = des;
//移动完毕,跳出循环
break;
}
}
if (temp < 0) {
//如果是数组目前的最大值,直接插入
arrays[index] = des;
}
index++;
temp = -1;
}
private void delete(int sub) {
for (int i = sub; i < arrays.length - 1; i++) {
arrays[i] = arrays[i + 1];
}
arrays[arrays.length - 1] = 0;
}
private void arrayInfo() {
for (int i = 0; i < arrays.length; i++) {
System.out.println("第" + i + "个元素是" + arrays[i]);
}
}
}