问题:
Suppose you have a random list of people standing in a queue. Each person is described by a pair of integers (h, k)
, where h
is the height of the person and k
is the number of people in front of this person who have a height greater than or equal to h
. Write an algorithm to reconstruct the queue.
Note:
The number of people is less than 1,100.
Example
Input: [[7,0], [4,4], [7,1], [5,0], [6,1], [5,2]] Output: [[5,0], [7,0], [5,2], [6,1], [4,4], [7,1]]
解决:
【题意】给出了一些人的身高和这个人前面身高大于等于他的人数,对这些人进行排队,使得所有人的情况都得到满足。
①
贪心算法:
(1)首先找到身高最高的人并对他们进行排序。
(2)然后找到身高次高的人,按照他们的前面的人数把他们插入到最高的人群中。
因此这是一个排序和插入的过程,按照身高进行降序排序,然后把身高相同的人按照k进行升序排序。每次取出身高相同的一组人,按照k值把他们插入到队列中。
class Solution { //17ms
public int[][] reconstructQueue(int[][] people) {
Arrays.sort(people, new Comparator<int[]>() {
@Override
public int compare(int[] o1, int[] o2) {//按照身高降序排序,按照k的大小升序排序
if (o1[0] != o2[0]){
return o2[0] - o1[0];
}else{
return o1[1] - o2[1];
}
}
});
List<int[]> res = new ArrayList<>();
for (int i = 0;i < people.length;i ++){
int[] p = people[i];
res.add(p[1],p);
}
return res.toArray(new int[people.length][]);
}
}