全排列（C++实现，回溯）

#include<bits/stdc++.h>
using namespace std;

int num = 0;

void swap(int A[], int x, int y) {
	int temp = A[x];
	A[x] = A[y];
	A[y] = temp;
}

void printA(int A[], int length) {
	for (int i = 0; i < length; i++) {
		cout << A[i] << " ";
	}
	cout << endl;
}

void next_permutation(int A[], int begin, int end) {
	if (begin == end) {
		num++;
		printA(A, end + 1);
	}
	else {
		for (int i = begin; i <= end; i++) {
			swap(A, begin, i);
			next_permutation(A, begin + 1, end);
			swap(A, begin, i);
		}
	}
}

int main() {
	int A[] = { 1,2,3,4 };
	next_permutation(A, 0, 2);
	cout << "总数是：" << num << endl;
	return 0;
}

测试结果：