#include <iostream>#include <algorithm>using namespace std;int main(){    int arr[4]={1,2,3,4};    do{        for(int i = 0; i < 4; i++){            cout << arr[i] << ‘ ‘;        }        cout << endl;    }while(next_permutation(arr,arr+4));    cout << "final state:" <<endl;    for(int i = 0; i < 4; i++){        cout << arr[i] << ‘ ‘;    }    cout << endl;    return 0;}

#include <iostream>using namespace std;template <class T>void Swap(T &a,T &b){    T temp = a;    a = b;    b = temp;}template <class T>void Swap(T list[],int i,int k){    T list_i = list[i];    if(i < k){        for(int j = i; j < k; j++){            list[j]= list[j+1];        }    }    else if(i > k){        for(int j = i; j>k; j--){            list[j]= list [j-1];        }    }    list[k] = list_i;}template <class T>void Perm(T list[],int k,int m){    if(k == m){        for(int i = 0; i <= m; i++){            cout << list[i] << ‘ ‘;        }        cout << endl;    }    else{        for(int i = k; i <= m; i++){            Swap(list, i, k);            Perm(list, k+1, m);            Swap(list, k, i);        }    }    return;}int main(){    int a[6]={1,2,3,4,5,6};    Perm(a,0,3);    return 0;}

#include <iostream>using namespace std;template <class T>void Swap(T &a,T &b){    T temp = a;    a = b;    b = temp;}template <class T>void Reverse(T list[], int i, int k){       //转置     T *listcpy = new T[k + 1];    for(int j = i; j <= k; j++){        listcpy[j] = list[i + k - j];    }    for(int j = i; j <= k; j++){        list[j] = listcpy[j];    }    delete listcpy;}template <class T>int Upper_Bound(T list[], int l, int r, T item){ //二分查找降序序列(l,r)中     int mid = (l + r + 1) / 2;                   //第一个大于item的位置     while(l < r){        mid = (l + r + 1) / 2;        if(list[mid] < item){            r = mid - 1;        }        else{            l = mid;        }    }    return l;}template <class T>bool Next_Permutation(T list[], int i, int k){    int n = -1, m = 0, t = k;    while(n == -1 && t != i){        if(list[t] > list[t-1]){   //n的位置             n = t - 1;        }        t--;    }    if(n == -1){                   //降序         Reverse(list, i, k);        return false;    }    else{        m = Upper_Bound(list, n+1, k, list[n]);   //m的位置         Swap(list[n], list[m]);       //交换n,m上的值         Reverse(list, n+1, k);        //倒置从n+1到k         return true;    }}int main(){    int arr[4]={1,2,3,4};    do{        for(int i = 0; i < 4; i++){            cout << arr[i] << ‘ ‘;        }        cout << endl;    }while(Next_Permutation(arr, 0, 3));    cout << "final state:" <<endl;    for(int i = 0; i < 4; i++){        cout << arr[i] << ‘ ‘;    }    cout << endl;    return 0;}