//字符串全排列
package com.demo.acm;public class AllSortChar {
public static void allSort(char[] buf,int start,int end){
if(start==end){
for(int i=0;i<=end;i++){
System.out.print(buf[i]);
}
System.out.println();
}else{
//多个字母全排列
for(int i=start;i<=end;i++){
char tmp=buf[start];//交换数组的第一个元素与后续的元素
buf[start]=buf[i];
buf[i]=tmp;
allSort(buf,start+1,end);//后续元素递归全排列
tmp=buf[start];//将交换后的数组还原
buf[start]=buf[i];
buf[i]=tmp;
}
}
}
public static void main(String[] args){
String test="abcd";
char[] chars=test.toCharArray();
allSort(chars, 0, chars.length-1);
}
}
//没有重复元素的排列
public class Solution {
public ArrayList<ArrayList<Integer>> permute(int[] num) {
ArrayList<ArrayList<Integer>> result = new ArrayList<ArrayList<Integer>>();if (null == num || num.length == 0)
return result;
int length = num.length;
if (length == 1) {
ArrayList<Integer> tmp = new ArrayList<Integer>();
tmp.add(num[0]);
result.add(tmp);
return result;
}
ArrayList<Integer> arrayList = null;
allPermutations(num, result,arrayList);
return result;
}
private void allPermutations(int[] num,
ArrayList<ArrayList<Integer>> result, ArrayList<Integer> arrayList) {
// TODO Auto-generated method stub
Arrays.sort(num);
int length = num.length;
int tmp;
while(true){
arrayList=new ArrayList<Integer>();
for(int i=0;i<length;i++)
arrayList.add(num[i]);
result.add(arrayList);
int i;
for(i=length-1;i>0;i--){
if(num[i]>num[i-1]){
break;
}
}
if(i<=0)
break;
int k;
for(k=i;k<length;k++){
if(k==length-1){
break;
}
if(num[k]>num[i-1]&&num[k+1]<num[i-1]){
break;
}
}
tmp=num[i-1];
num[i-1]=num[k];
num[k]=tmp;
sortArrays(num, i, length-1);
}
}
private void sortArrays(int[] num,int i,int j){
int beg=i;
int end=j;
int tmp;
while(beg<end){
tmp=num[beg];
num[beg]=num[end];
num[end]=tmp;
beg++;
end--;
}
}