Description
Given k sorted integer arrays, merge them into one sorted array.
Example
Example 1:
Input:
[
[1, 3, 5, 7],
[2, 4, 6],
[0, 8, 9, 10, 11]
]
Output: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11]
Example 2:
Input:
[
[1,2,3],
[1,2]
]
Output: [1,1,2,2,3]
Challenge
Do it in O(N log k).
N is the total number of integers.
k is the number of arrays.
思路：
1.分治法两两归并
2.用堆
基本思路和577的完全一样，只不过577合并区间的方法稍微复杂一点。
代码：
