README_EN.md

1051. Height Checker

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Description

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

Solutions

Python3

class Solution:
    def heightChecker(self, heights: List[int]) -> int:
        bucket = [0] * 101
        for h in heights:
            bucket[h] += 1
        res = i = 0
        for j in range(1, 101):
            while bucket[j] > 0:
                bucket[j] -= 1
                if heights[i] != j:
                    res += 1
                i += 1
        return res

class Solution:
    def heightChecker(self, heights: List[int]) -> int:
        expected = sorted(heights)
        return sum(1 for i, h in enumerate(heights) if h != expected[i])

Java

class Solution {
    public int heightChecker(int[] heights) {
        int[] expected = Arrays.copyOf(heights, heights.length);
        Arrays.sort(expected);
        int res = 0;
        for (int i = 0; i < heights.length; ++i) {
            if (heights[i] != expected[i]) {
                ++res;
            }
        }
        return res;
    }
}

C++

class Solution {
public:
    int heightChecker(vector<int>& heights) {
        vector<int> expected = heights;
        sort(expected.begin(), expected.end());
        int res = 0;
        for (int i = 0; i < heights.size(); ++i)
        {
            if (heights[i] != expected[i]) ++res;
        }
        return res;
    }
};

Go

func heightChecker(heights []int) int {
    expected := make([]int, len(heights))
    copy(expected, heights)
    sort.Ints(expected)
    res := 0
    for i, h := range heights {
        if h != expected[i] {
            res++
        }
    }
    return res
}

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