字符串的排列

#include <iostream>
#include <cmath>
using namespace std;
void MyPermutition(char * a,int length,int index)
{
	if(index == length -1)
	{
		for(int i = 0;i < length;++i)
			cout<<a[i];
		cout<<endl;
		return;
	}
	else
	{
		for(int i = index; i < length ;++i)
		{
			swap(a[i],a[index]);
			MyPermutition (a,length,index+1);
			swap(a[i],a[index]);
		}
	}
}

void MyReverse(char *a,int start,int length)
{
	for(int i = start,j = length -1; i < j;++i,--j)
	{
		swap(a[i],a[j]);
	}
}

bool ZiDianXuNext(char *a,int length)
{
   int i = 0;//满足 p[j-1] < p[j] j的最大值
   int h = 0; //满足 p[i-1] < p[k] k的最大值
   for(int t = 1;t < length;++t)
   {
	   	if(a[t - 1] < a[t]) i = t;
   }
   if(i == 0)return false;//没找到满足	p[j-1] < p[j] 的情况 说明已经到头了
   for(int t = 0 ;t < length ;++t)
   {
	   if(a[t] > a[i-1])h = t;// 满足 p[i-1] < p[k] k的最大值
   }
   swap(a[i-1],a[h]);
   MyReverse(a,i,length);	//逆序后面的元素
   for(int t = 0 ; t< length;++t)
   {
	   cout<<a[t];	   
   }
   cout<<endl;
   return true;
}


int main()
{

	char a[4] = {'1','2','3','4'};
	while (ZiDianXuNext(a,4));
	getchar();

	return 0;
}