POJ 3050 Hopscotch

http://poj.org/problem?id=3050

深搜 + set去重

这道题的深搜很简单 每满六次后 insertin进set即可 最终果就是set.size()

#include <iostream>
#include <fstream>
#include <stdio.h>
#include <string>
#include <set>

using namespace std;

string srec;
char rec[8];
int d[4][2] = { {-1,0}, {0, 1}, {1, 0}, {0, -1} };
int grid[8][8];

set<string> str_set;

bool check(int x, int y)
{
    if (x < 0 || y < 0 || x >= 5 || y >= 5) return false;
    return true;
}

void dfs(int x, int y, int n)//深搜的话 O(n^2*4^5*nlogn) --->>> 25*4^5*nlogn 数据小还好 用set消重
{
    if (n == 6)
    {
        srec = rec;
        str_set.insert(srec);
        return ;
    }
    rec[n] = grid[x][y] + '0';//记录这个格子里的数
    for (int i = 0; i < 4; i++)
    {
        if (check(x+d[i][0], y+d[i][1]))//越界检查
        {
            dfs(x+d[i][0], y+d[i][1], n+1);
        }
    }
}

int main()
{
    freopen("in.txt", "r", stdin);
    ofstream cout ("out.txt");
    for (int i = 0; i < 5; i++)
    {
        for (int j = 0;j < 5; j++)
        {
            scanf("%d", &grid[i][j]);
        }
    }
    for (int i = 0; i < 5; i++)
    {
        for (int j = 0; j < 5; j++)
        {
            dfs(i,j,0);
        }
    }
    printf("%d", str_set.size());
    return 0;
}