void rotate_helper(vector<vector<int>> &matrix, int s,int e){
if(s==e)
return;
if(s+1==e){
swap(matrix[s][s], matrix[s][s+1]);
swap(matrix[s+1][s], matrix[s+1][s+1]);
swap(matrix[s][s], matrix[e][e]);
return;
}
rotate_helper(matrix, s+1, e-1);
//左右调换
int p=s,q=e;
while(p<=q){
swap(matrix[s][p], matrix[s][q]);
swap(matrix[e][p], matrix[e][q]);
p++;
q--;
}
for(int i=s+1;i<=e-1;i++){
swap(matrix[i][s], matrix[i][e]);
}
//斜调换
for(int k=s+1;k<=e;k++){
swap(matrix[k][e], matrix[s][s+e-k]);
}
for(int k=s+1;k<=e-1;k++){
swap(matrix[e][k], matrix[s+e-k][s]);
}
return;
}
static typename detail::algorithm_result<ExPolicy, FwdIter>::type
parallel(ExPolicy const& policy, FwdIter first,
FwdIter new_first, FwdIter last)
{
return detail::algorithm_result<ExPolicy, FwdIter>::get(
rotate_helper(policy, first, new_first, last));
}
void rotate(vector<vector<int> > &matrix) {
rotate_helper(matrix, 0, matrix.size()-1);
}
list_t rotate(list_t list, unsigned int n) {
return rotate_helper(list, n, list_make());
}
static list_t rotate_helper(list_t list, unsigned int n, list_t rotated) {
if (!n) return append(list, reverse(rotated));
if (list_isEmpty(list) && n) rotate_helper(reverse(rotated), n-1, list_make());
return rotate_helper(list_rest(list), n-1,
list_make(list_first(list), rotated));
}
