对于一个int数组,请编写一个计数排序算法,对数组元素排序。
给定一个int数组A及数组的大小n,请返回排序后的数组。
测试样例:
[1,2,3,5,2,3],6
[1,2,2,3,3,5]
我的提交
-- coding:utf-8 --
class CountingSort:
def countingSort(self, A, n):
write code here
seta = set(A)
minnum = min(seta)
maxnum = max(seta)
buckets = {}
for i in range(minnum, maxnum+1):
buckets[i] = 0
for num in range(n):
buckets[A[num]] = buckets[A[num]] + 1
B = []
for j in range(minnum, maxnum+1):
B.extend([j] * buckets[j])
return B
if name == 'main':
c = CountingSort()
print(c.countingSort([54,35,48,36,27,12,44,44,8,14,26,17,28],13))
调整一下,减少空间消耗
-- coding:utf-8 --
class CountingSort:
def countingSort(self, A, n):
write code here
seta = set(A)
minnum = min(seta)
maxnum = max(seta)
buckets = {}
for i in range(minnum, maxnum+1):
buckets[i] = 0
for num in range(n):
buckets[A[num]] = buckets[A[num]] + 1
i = 0
for j in range(minnum, maxnum+1):
for _ in range(buckets[j]):
A[i] = j
i += 1
return A
if name == 'main':
c = CountingSort()
print(c.countingSort([54,35,48,36,27,12,44,44,8,14,26,17,28],13))
参考答案
public class CountSort {
public static void countSort(int[] arr) {
if (arr == null || arr.length < 2) {
return;
}
int min = arr[0];
int max = arr[0];
for (int i = 1; i < arr.length; i++) {
min = Math.min(arr[i], min);
max = Math.max(arr[i], max);
}
int[] countArr = new int[max - min + 1];
for (int i = 0; i < arr.length; i++) {
countArr[arr[i] - min]++;
}
int index = 0;
for (int i = 0; i < countArr.length; i++) {
while (countArr[i]-- > 0) {
arr[index++] = i + min;
}
}
}
public static void swap(int[] arr, int index1, int index2) {
int tmp = arr[index1];
arr[index1] = arr[index2];
arr[index2] = tmp;
}
public static int[] generateArray(int len, int range) {
if (len < 1) {
return null;
}
int[] arr = new int[len];
for (int i = 0; i < len; i++) {
arr[i] = (int) (Math.random() * range);
}
return arr;
}
public static void printArray(int[] arr) {
if (arr == null || arr.length == 0) {
return;
}
for (int i = 0; i < arr.length; i++) {
System.out.print(arr[i] + " ");
}
System.out.println();
}
public static boolean isSorted(int[] arr) {
if (arr == null || arr.length < 2) {
return true;
}
for (int i = 1; i < arr.length; i++) {
if (arr[i - 1] > arr[i]) {
return false;
}
}
return true;
}
public static void main(String[] args) {
int len = 10;
int range = 10;
int testTimes = 50000;
for (int i = 0; i < testTimes; i++) {
int[] arr = generateArray(len, range);
countSort(arr);
if (!isSorted(arr)) {
System.out.println("Wrong Case:");
printArray(arr);
break;
}
}
int len2 = 13;
int range2 = 10;
int testTimes2 = 50000;
for (int i = 0; i < testTimes2; i++) {
int[] arr = generateArray(len2, range2);
countSort(arr);
if (!isSorted(arr)) {
System.out.println("Wrong Case:");
printArray(arr);
break;
}
}
}
}