Data Stream Median(数据流中位数)

问题

Numbers keep coming, return the median of numbers at every time a new number added.

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Clarification
What's the definition of Median?

• Median is the number that in the middle of a sorted array. If there are n numbers in a sorted array A, the median is A[(n - 1) / 2]. For example, if A=[1,2,3], median is 2. If A=[1,19], median is 1.

Example
For numbers coming list: [1, 2, 3, 4, 5], return [1, 1, 2, 2, 3].

For numbers coming list: [4, 5, 1, 3, 2, 6, 0], return [4, 4, 4, 3, 3, 3, 3].

For numbers coming list: [2, 20, 100], return [2, 2, 20].

分析

构造一个List来存储数据，然后使用系统自带的查找方法找到需要插入的位置。

代码

public class Solution {
    /*
     * @param nums: A list of integers
     * @return: the median of numbers
     */
    public int[] medianII(int[] nums) {
        // write your code here
        int[] res = new int[nums.length];
        List list = new ArrayList<>();
        for (int i = 0; i < nums.length; i++) {
            int temp = nums[i];
            if (i == 0) {
                list.add(temp);
                res[i] = temp;
            } else {
                int index = Collections.binarySearch(list, temp);
                if (index < 0) {
                    index++;
                    index = -index;
                }
                list.add(index, temp);
                res[i] = list.get((list.size() - 1) >>> 1);
            }
        }
        return res;
    }
}