C++ 程序实现 STL 中的 Prev_Permutataion
STL 中的 Prev_permutation 用于将范围 [first, last] 中的元素重新排列为先前的字典序较小排列。排列是指元素可以采取的 N! 种可能排列中的每一种。以下是一个 C++ 程序,用于实现 STL 中的 Prev_permutation。
算法
Begin Define one integer array variable elements[]. Get the number of data e from the user. Initialize the array elements[] with e number of data from the keyboard. Sort all the array elements. Reverse the array elements. Do show(elements) //to display the current content of the array while (prev_permutation(elements, elements + e)) End.
示例代码
#include<iostream>
#include <algorithm>
using namespace std;
void show(int a[], int n) {
for(int i = 0; i < n; i++) {
cout<<a[i]<<" ";
}
cout<<endl;
}
int main () {
int e, i;
cout<<"Enter number of elements to be inserted: ";
cin>>e;
int elements[e];
for (i = 0; i < e; i++) {
cout<<"Enter "<<i + 1<<" element: ";
cin>>elements[i];
}
sort (elements, elements + e);
reverse (elements, elements + e);
cout << "The "<<e<<"! possible permutations with ";
cout<<e<<" elements: "<<endl;
do {
show(elements, e);
}
while (prev_permutation(elements, elements + e));
return 0;
}输出
Enter number of elements to be inserted: 4 Enter 1 element: 7 Enter 2 element: 6 Enter 3 element: 10 Enter 4 element: 2 The 4! possible permutations with 4 elements: 10 7 6 2 10 7 2 6 10 6 7 2 10 6 2 7 10 2 7 6 10 2 6 7 7 10 6 2 7 10 2 6 7 6 10 2 7 6 2 10 7 2 10 6 7 2 6 10 6 10 7 2 6 10 2 7 6 7 10 2 6 7 2 10 6 2 10 7 6 2 7 10 2 10 7 6 2 10 6 7 2 7 10 6 2 7 6 10 2 6 10 7 2 6 7 10
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