POJ 2488 A Knight's Journey ----- DFS

Vontroy — Wed, 28 Jul 2010 23:18:00 GMT

#include <stdio.h>
#include <string.h>

const int maxn = 50;

int b[8]={-2, -2, -1, -1, 1, 1, 2, 2},a[8]={-1, 1, -2, 2, -2, 2, -1, 1};
bool check[maxn][maxn], flag;
int ansx[maxn], ansy[maxn];
int row, col;

void dfs(int x, int y, int sum)
{
    if(sum == col * row)
    {
        for(int i=1; i<=sum; i++)
        printf("%c%d", ansy[i]+'A'-1, ansx[i]);
        printf("\n");
        flag=1;
        return;
    }
    for(int i=0; i<8 && !flag; i++)
    {
        if(!flag && !check[x+a[i]][y+b[i]] && x+a[i]>0 && x+a[i]<=row && y+b[i]>0 && y+b[i]<=col)
        {
            ansx[sum+1] = x+a[i];
            ansy[sum+1] = y+b[i];
            check[x+a[i]][y+b[i]] = 1;
            dfs(x+a[i], y+b[i], sum+1);
            check[x+a[i]][y+b[i]] = 0;
        }
    }
}

int main()
{
    int n;
    int cas;
    while(~scanf("%d",&n))
    {
        cas=1;
        while(n--)
        {
            flag = 0;
            memset(check,0,sizeof(check));
            printf("Scenario #%d:\n",cas++);
            scanf("%d%d", &row, &col);
            check[1][1]=1;
            ansx[1] = ansy[1] = 1;
            dfs(1, 1, 1);
            if(!flag) printf("impossible\n");
            printf("\n");
        }
    }
    return 0;
}

Vontroy 2010-07-29 07:18 发表评论

HDU 1010 Tempter of the Bone

Vontroy — Wed, 28 Jul 2010 22:58:00 GMT

#include <iostream>
#include <cstdio>
#include <cmath>

const int maxn = 10;

using namespace std;

bool escape;

char map[maxn][maxn];

int dir[4][2] = {{-1,0}, {1,0}, {0,-1}, {0,1}};
int n, m, t;
int si, sj, di, dj;

void dfs( int x, int y, int cnt )
{
    if( escape ) return;

    if( x == di && y == dj && cnt == t )
    {
        escape = 1;
        return;
    }

    int temp = t - cnt - ( fabs(di - x) + fabs(dj - y ) );

    if( temp < 0 || temp % 2 != 0 )     return;//奇偶剪枝

    if( x <= 0 || y <= 0 || x > n || y > m )    return;

    for( int i = 0; i < 4; i++ )
    {
        if( map[x+dir[i][0]][y+dir[i][1]] != 'X')
        {
            map[x+dir[i][0]][y+dir[i][1]] = 'X';
            dfs(x+dir[i][0], y+dir[i][1], cnt+1);
            map[x+dir[i][0]][y+dir[i][1]] = '.';
        }
    }

}

int main()
{
    while( cin >> n >> m >> t, m || n || t )
    {
        int wall = 0;
        escape = 0;
        for ( int i = 1; i <= n; i++ )
            for ( int j = 1; j <= m; j++ )
            {
                cin >> map[i][j];

                if( map[i][j] == 'D')
                {
                    di = i;
                    dj = j;
                }

                else if ( map[i][j] == 'S' )
                {
                    si = i;
                    sj = j;
                }

                else if ( map[i][j] == 'X' )
                    wall ++ ;
            }

        if( m * n - wall <= t )
        {
            printf("NO\n");
            continue;
        }
        else
        {
            map[si][sj] = 'X';
            dfs( si, sj, 0 );
            printf("%s\n", escape ? "YES" : "NO" );
        }
    }
    return 0;
}

Vontroy 2010-07-29 06:58 发表评论

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POJ 2488 A Knight's Journey ----- DFS

HDU 1010 Tempter of the Bone