经典算法实现之桶排序

算法

桶排序（Bucket sort）或所谓的箱排序，是一个排序算法，工作的原理是将数组分到有限数量的桶里。每个桶再个别排序（有可能再使用别的排序算法或是以递归方式继续使用桶排序进行排序），最后依次把各个桶中的记录列出来记得到有序序列。桶排序是鸽巢排序的一种归纳结果。

实现

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
// C++ program to sort an array using bucket sort
#include <algorithm>
#include <iostream>
#include <vector>

// Function to sort arr[] of size n using bucket sort
void bucketSort(float arr[], int n) {
    // 1) Create n empty buckets
    std::vector<float> *b = new std::vector<float>[n];

    // 2) Put array elements in different buckets
    for (int i = 0; i < n; i++) {
        int bi = n * arr[i];  // Index in bucket
        b[bi].push_back(arr[i]);
    }

    // 3) Sort individual buckets
    for (int i = 0; i < n; i++) std::sort(b[i].begin(), b[i].end());

    // 4) Concatenate all buckets into arr[]
    int index = 0;
    for (int i = 0; i < n; i++)
        for (int j = 0; j < b[i].size(); j++) arr[index++] = b[i][j];
    delete[] b;
}

/* Driver program to test above funtion */
int main() {
    float arr[] = {0.897, 0.565, 0.656, 0.1234, 0.665, 0.3434};
    int n = sizeof(arr) / sizeof(arr[0]);
    bucketSort(arr, n);

    std::cout << "Sorted array is \n";
    for (int i = 0; i < n; i++) std::cout << arr[i] << " ";
    return 0;
}