POJ 1915

1. 简单的bfs，有用双向bfs的，但是为了赶进度，以后用双向bfs实现

#include <iostream>
#include <fstream>
#include <string>
#include <algorithm>
#include <cstring>
#include <stack>
#include <queue>

using namespace std;
int dir[8][2] = {{-2, 1}, {-1, 2}, {1, 2}, {2, 1}, {2, -1}, {1, -2}, {-1, -2}, {-2, -1}};
int flag[301][301], step[301][301];
int n, len, i;
struct Node
{
    int x, y;
} s, t;
void bfs()
{
    queue<Node> q;
    q.push(s);
    while (!q.empty())
    {
        Node temp = q.front(), nex;
        flag[temp.x][temp.y] = 1;
        if (temp.x == t.x && temp.y == t.y)
        {
            cout << step[temp.x][temp.y] << endl;
            return;
        }
        q.pop();
        for (i = 0; i < 8; i++)
        {
            nex.x = temp.x + dir[i][0];
            nex.y = temp.y + dir[i][1];
            if (nex.x < len && nex.x >= 0 && nex.y < len && nex.y >= 0 && !flag[nex.x][nex.y])
            {
                q.push(nex);
                step[nex.x][nex.y] = step[temp.x][temp.y] + 1;
                flag[nex.x][nex.y] = 1;
            }
        }
    }
}
int main()
{
    cin >> n;
    while (n--)
    {
        cin >> len >> s.x >> s.y >> t.x >> t.y;
        memset(flag, 0, sizeof(flag));
        memset(step, 0, sizeof(step));
        step[s.x][s.y] = 0;
        bfs();
    }
    return 0;
}