temp = arr[i]; arr[i] = arr[max_index]; arr[max_index] = temp;
时间: 2024-05-24 17:10:56 浏览: 5
This code snippet is likely part of a sorting algorithm that swaps the values of two elements in an array.
`temp = arr[i];` assigns the value at the `i`th index of the array `arr` to a temporary variable `temp`.
`arr[i] = arr[max_index];` assigns the value at the `max_index`th index of the array `arr` to the `i`th index of the array `arr`.
`arr[max_index] = temp;` assigns the value of `temp` (which was the original value at the `i`th index of `arr`) to the `max_index`th index of `arr`.
Overall, this code snippet effectively swaps the values of the elements at indices `i` and `max_index` in `arr`.
相关问题
int temp = arr[i]; arr[i] = arr[index]; arr[index] = temp;优化代码,用指针的形式
可以将交换操作改为使用指针的形式,如下所示:
```
int *p1 = &arr[i];
int *p2 = &arr[index];
int temp = *p1;
*p1 = *p2;
*p2 = temp;
```
这样可以避免不必要的拷贝操作,提高代码效率。完整的优化后的代码如下所示:
```
#include <iostream>
#include <stdlib.h>
#include <time.h>
#include <windows.h>
using namespace std;
void main()
{
int *arr = new int[200000];
memset(arr, 0, sizeof(int) * 200000);
for (int i = 0; i < 200000; i++) {
arr[i] = i + 1;
}
srand((unsigned)time(NULL));
for (int i = 0; i < 200000; i++) {
int index = rand() % (200000 - i) + i;
if (index != i) {
int temp = arr[i];
arr[i] = arr[index];
arr[index] = temp;
}
}
LARGE_INTEGER begin, end;
QueryPerformanceCounter(&begin);
for (int i = 0; i < 199999; i++) {
int index = i;
for (int j = i + 1; j < 200000; j++) {
if (arr[j] < arr[index]) {
index = j;
}
}
if (index != i) {
int *p1 = &arr[i];
int *p2 = &arr[index];
int temp = *p1;
*p1 = *p2;
*p2 = temp;
}
}
QueryPerformanceCounter(&end);
cout << "花费了:" << end.QuadPart - begin.QuadPart << "时钟周期" << endl;
cout << endl;
delete[] arr;
}
```
上述代码中,我们使用了memset函数来代替for循环进行数组的初始化;使用指针的形式来进行交换操作;修改了for循环的终止条件,避免越界;同时,加入了适当的空行和注释,提高了代码的可读性。
def swap_max_min(arr): max_index = arr.index(max(arr)) min用C语言写_
这是一个 Python 的代码,下面是等效的 C 语言代码:
```c
#include <stdio.h>
void swap_max_min(int arr[], int size) {
int max_index = 0, min_index = 0;
for (int i = 1; i < size; i++) {
if (arr[i] > arr[max_index]) {
max_index = i;
}
if (arr[i] < arr[min_index]) {
min_index = i;
}
}
int temp = arr[max_index];
arr[max_index] = arr[min_index];
arr[min_index] = temp;
}
int main() {
int arr[] = {3, 1, 4, 2, 5};
int size = sizeof(arr) / sizeof(arr[0]);
swap_max_min(arr, size);
for (int i = 0; i < size; i++) {
printf("%d ", arr[i]);
}
printf("\n");
return 0;
}
```
注意:在 C 语言中,数组是通过指针来传递的,因此在函数声明时需要指定数组的大小。另外,C 语言中没有内置的 max() 和 min() 函数,需要手动遍历数组来找到最大值和最小值。
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