#include<iostream>; #include<time.h>; using namespace std; void main(){ int* arr = (int*)malloc(500000 * sizeof(int)); for (int i = 0;i < 500000;i++) { srand((unsigned)time(NULL)); arr[i]=(rand() % 500000) + 1; cout << arr[i] << endl; } }优化代码
时间: 2023-12-05 15:04:31 浏览: 40
这段代码可以进行如下优化:
1. 使用 new/delete 代替 malloc/free,以避免出现内存泄漏。
2. 将 srand 移到循环外部,避免重复设置种子。
3. 将 cout 操作从循环中移出,避免过多的输出操作。
4. 将 for 循环改为 while 循环,使用前缀自增运算符代替后缀自增运算符,以提高代码效率。
优化后的代码如下所示:
```
#include <iostream>
#include <cstdlib>
#include <ctime>
using namespace std;
int main() {
int* arr = new int[500000];
srand((unsigned)time(NULL)); // 移到循环外部
int i = 0;
while (i < 500000) { // 改为 while 循环
arr[i] = (rand() % 500000) + 1;
++i; // 使用前缀自增运算符
}
for (i = 0; i < 500000; ++i) {
cout << arr[i] << endl;
}
delete[] arr; // 使用 delete 释放内存
return 0;
}
```
经过优化后,代码更加简洁、高效、易读、易维护,同时也避免了内存泄漏等问题。
相关问题
#include <iostream>#include <ctime>#include <cstdlib>using namespace std;const int MAXN = 500; // 需要排序的数组大小const int MAXV = 2000; // 随机数的最大值// 直接插入排序void insertSort(int a[], int
Sure, I can help you with that. The code you provided is written in C++ and it seems to be implementing the insertion sort algorithm. Insertion sort is a simple sorting algorithm that works by repeatedly inserting elements into a sorted portion of the array.
Here's the complete implementation of the insertion sort algorithm based on the code you provided:
```cpp
#include <iostream>
#include <ctime>
#include <cstdlib>
using namespace std;
const int MAXN = 500; // Size of the array to be sorted
const int MAXV = 2000; // Maximum value for random numbers
// Function to generate random numbers
void generateRandomArray(int a[], int n) {
srand(time(0));
for (int i = 0; i < n; i++) {
a[i] = rand() % MAXV;
}
}
// Function to print the array
void printArray(int a[], int n) {
for (int i = 0; i < n; i++) {
cout << a[i] << " ";
}
cout << endl;
}
// Insertion sort implementation
void insertionSort(int a[], int n) {
for (int i = 1; i < n; i++) {
int key = a[i];
int j = i - 1;
while (j >= 0 && a[j] > key) {
a[j + 1] = a[j];
j--;
}
a[j + 1] = key;
}
}
int main() {
int arr[MAXN];
// Generate random array
generateRandomArray(arr, MAXN);
cout << "Original array: ";
printArray(arr, MAXN);
// Sort the array using insertion sort
insertionSort(arr, MAXN);
cout << "Sorted array: ";
printArray(arr, MAXN);
return 0;
}
```
This code generates a random array of size `MAXN` with values ranging from 0 to `MAXV`. It then sorts the array using the insertion sort algorithm and prints the original and sorted arrays.
Let me know if you have any further questions or if there's anything else I can assist you with!
#include <algorithm> #include <iostream> using namespace std; int main() { int n; cin >> n; int* c = new int[n]; for (int i = 0; i < n; i++) cin >> c[i]; sort(c, c + n); do { for (int i = 0; i < n; i++) cout << c[i]<<" "; cout << endl; } while (next_permutation(c, c + n)); return 0; }不用do while怎么写
可以使用递归的方式来实现全排列,具体实现如下:
```
#include <algorithm>
#include <iostream>
using namespace std;
void permutation(int* arr, int start, int end)
{
if(start == end)
{
for(int i = 0; i <= end; i++)
cout << arr[i] << " ";
cout << endl;
}
else
{
for(int i = start; i <= end; i++)
{
swap(arr[start], arr[i]);
permutation(arr, start+1, end);
swap(arr[start], arr[i]);
}
}
}
int main()
{
int n;
cin >> n;
int* arr = new int[n];
for(int i = 0; i < n; i++)
cin >> arr[i];
sort(arr, arr + n);
permutation(arr, 0, n-1);
delete[] arr;
return 0;
}
```
这个程序与之前的程序有很大的相似性,只是将do-while循环改为了递归函数。程序先对输入的元素进行排序,然后调用递归函数permutation来进行全排列。递归终止条件是只剩下一个元素时,直接输出即可。
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