1051. Height Checker

Easy

A school is trying to take an annual photo of all the students. The students are asked to stand in a single file line in non-decreasing order by height. Let this ordering be represented by the integer array expected where expected[i] is the expected height of the ith student in line.

You are given an integer array heights representing the current order that the students are standing in. Each heights[i] is the height of the ith student in line (0-indexed).

Return the number of indices where heights[i] != expected[i].

Example 1:

Input: heights = [1,1,4,2,1,3]
Output:
 3
Explanation:
 
heights:  [1,1,4,2,1,3]
expected: [1,1,1,2,3,4]
Indices 2, 4, and 5 do not match.

Example 2:

Input: heights = [5,1,2,3,4]
Output:
 5
Explanation:
heights:  [5,1,2,3,4]
expected: [1,2,3,4,5]
All indices do not match.

Example 3:

Input: heights = [1,2,3,4,5]
Output:
 0
Explanation:
heights:  [1,2,3,4,5]
expected: [1,2,3,4,5]
All indices match.

Constraints:

• 1 <= heights.length <= 100

• 1 <= heights[i] <= 100

解題

時間複雜度: log(n)

Runtime: 0 ms, faster than 100.00%

Memory Usage: 2.3 MB, less than 72.22%

func heightChecker(heights []int) int {
    count := [100]int{0}
    
    for _, val := range(heights) {
        count[val-1]++
    }
    
    index := 0
    ans := 0
    for i:=0; i<100; i++ {
        for count[i]>0 {
            if heights[index]!=i+1 {
                ans++
            }
            count[i]--
            index++
        }
    }
    
    return ans
}