SRM 397 DIV2 [500]

 

#include<iostream>
#include<queue>
#include<vector>
#include<set>
#include<algorithm>
using namespace std;

vector<int> swap(vector<int> a,int beg,int len)
...{
    int mid=len/2,end=beg+len-1;;
    for (int i=0;i!=mid;++i)...{
        int temp=a[beg+i];
        a[beg+i]=a[end-i];
        a[end-i]=temp;
    }
    return a;
}

class SortingGame...{
public:
    int fewestMoves(vector<int> a,int num)
    ...{
        int len=a.size();
           vector<int> des(a);
        sort(des.begin(),des.end());
        if (des==a) return 0;
        set<vector<int> > vis;
        vis.insert(a);
        queue<vector<int> > qData;
        qData.push(a);
        queue<int> qTime;
        qTime.push(0);
        while (!qData.empty())...{
            for (int i=0;i!=len-num+1;++i)...{
                vector<int> temp(swap(qData.front(),i,num) );
                if (temp==des)     return ++qTime.front();
                if (!vis.count(temp))...{
                    vis.insert(temp);
                    qTime.push(qTime.front()+1);
                    qData.push(temp);
                }
            }
            qData.pop();
            qTime.pop();
        }
        return -1;
    }
};

Problem Statement
	In The Sorting Game, you are given a sequence containing a permutation of the integers between 1 and n, inclusive. In one move, you can take any k consecutive elements of the sequence and reverse their order. The goal of the game is to sort the sequence in ascending order. You are given a vector <int> board describing the initial sequence. Return the fewest number of moves necessary to finish the game successfully, or -1 if it's impossible.
Definition
	Class: SortingGame Method: fewestMoves Parameters: vector <int>, int Returns: int Method signature: int fewestMoves(vector <int> board, int k) (be sure your method is public)
Constraints
-	board will contain between 2 and 8 elements, inclusive.
-	Each integer between 1 and the size of board, inclusive, will appear in board exactly once.
-	k will be between 2 and the size of board, inclusive.
Examples
0)
	{1,2,3} 3 Returns: 0 The sequence is already sorted, so we don't need any moves.
1)
	{3,2,1} 3 Returns: 1 We can reverse the whole sequence with one move here.
2)
	{5,4,3,2,1} 2 Returns: 10 This one is more complex.
3)
	{3,2,4,1,5} 4 Returns: -1
4)
	{7,2,1,6,8,4,3,5} 4 Returns: 7

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