1051. Height Checker

# 1051. Height Checker#

## 题目 #

Students are asked to stand in non-decreasing order of heights for an annual photo.

Return the minimum number of students that must move in order for all students to be standing in non-decreasing order of height.

Notice that when a group of students is selected they can reorder in any possible way between themselves and the non selected students remain on their seats.

Example 1:

``````Input: heights = [1,1,4,2,1,3]
Output: 3
Explanation:
Current array : [1,1,4,2,1,3]
Target array  : [1,1,1,2,3,4]
On index 2 (0-based) we have 4 vs 1 so we have to move this student.
On index 4 (0-based) we have 1 vs 3 so we have to move this student.
On index 5 (0-based) we have 3 vs 4 so we have to move this student.
``````

Example 2:

``````Input: heights = [5,1,2,3,4]
Output: 5
``````

Example 3:

``````Input: heights = [1,2,3,4,5]
Output: 0
``````

Constraints:

• `1 <= heights.length <= 100`
• `1 <= heights[i] <= 100`

## 解题思路 #

• 给定一个高度数组，要求输出把这个数组按照非递减高度排列所需移动的最少次数。
• 简单题，最少次数意味着每次移动，一步到位，一步就移动到它所在的最终位置。那么用一个辅助排好序的数组，一一比对计数即可。

## 代码 #

``````
package leetcode

func heightChecker(heights []int) int {
result, checker := 0, []int{}
checker = append(checker, heights...)
sort.Ints(checker)
for i := 0; i < len(heights); i++ {
if heights[i] != checker[i] {
result++
}
}
return result
}

``````

Sep 6, 2020