HDU 1813 Escape from Tetris

Posted 2020-08-27 ziliuziliu

TMDTMD

IDA*没跑了。什么是IDA*？

就是迭代深搜+A*估个价。

然而为什么调了一天？

n<=2的时候我输出了东西。。。。

看了一天。

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<queue>
#define maxn 15
#define inf 2000000000
using namespace std;
int n,map[maxn][maxn],tot=0,dis[maxn][maxn],mx=0,ans[maxn*maxn*maxn],d,dr[maxn][maxn];
int dx[]={0,0,-1,1,0},dy[]={0,1,0,0,-1};
char s[maxn];
queue <int> q;
struct point
{
    int x,y;
    point (int x,int y):x(x),y(y) {}
    point () {}
}p[maxn*maxn];
bool bnd(int x,int y)
{
    if ((x==1) || (x==n) || (y==1) || (y==n)) return true;
    return false;
}
bool judge(int x,int y)
{
    if ((x>=1) && (x<=n) && (y>=1) && (y<=n)) return true;
    return false;
}
int bfs(int x,int y)
{
    for (int i=1;i<=n;i++)
        for (int j=1;j<=n;j++)
            dr[i][j]=inf;
    while (!q.empty()) q.pop();
    dr[x][y]=0;q.push(x);q.push(y);
    while (!q.empty())
    {
        int hx,hy;
        hx=q.front();q.pop();hy=q.front();q.pop();
        if (bnd(hx,hy)) return dr[hx][hy];
        for (int i=1;i<=4;i++)
        {
            int tx=hx+dx[i],ty=hy+dy[i];
            if ((map[tx][ty]) && (dr[tx][ty]==inf) && (judge(tx,ty)))
            {
                q.push(tx);q.push(ty);
                dr[tx][ty]=dr[hx][hy]+1;
            }
        }
    }
    return inf;
}
int gets_h(point p[])
{
    int mx=0;
    for (int i=1;i<=tot;i++) mx=max(mx,dis[p[i].x][p[i].y]);
    return mx;
}
point modify(point x,int y)
{
    if (bnd(x.x,x.y)) return x;
    point now=point(x.x+dx[y],x.y+dy[y]);
    if ((!map[now.x][now.y]) || (!judge(now.x,now.y))) return x;
    else return now;
}
bool IDA(int deep,point p[])
{
    point node[maxn*maxn];
    if (gets_h(p)+deep>d) return false;
    if (deep==d) return true;
    for (int i=1;i<=4;i++)
    {
        ans[deep]=i;
        for (int j=1;j<=tot;j++) node[j]=modify(p[j],i);
        if (IDA(deep+1,node)) return true;
    }
    return false;
}
void work()
{
    tot=0;memset(ans,0,sizeof(ans));
    for (int i=1;i<=n;i++)
        for (int j=1;j<=n;j++)
            dis[i][j]=-1;
    for (int i=1;i<=n;i++)
    {
        scanf("%s",s);
        for (int j=1;j<=n;j++)
        {
            if (s[j-1]==‘0‘) map[i][j]=1;
            else map[i][j]=0;
            if ((map[i][j]) && (!bnd(i,j))) p[++tot]=point(i,j);
        }
    }
    if (!tot) return;
    for (int i=1;i<=n;i++)
        for (int j=1;j<=n;j++)
        {
            if (!map[i][j]) dis[i][j]=inf;
            else
            {
                if (bnd(i,j)) dis[i][j]=0;
                else dis[i][j]=bfs(i,j);
                mx=max(mx,dis[i][j]);
                if (dis[i][j]==inf) {printf("CX_naive\n");return;}
            }
        }
    for (d=1;;d++)    
    {
        if (IDA(0,p))
        {
            for (int j=0;j<d;j++)
            {
                if (ans[j]==1) printf("east\n");
                else if (ans[j]==2) printf("north\n");
                else if (ans[j]==3) printf("south\n");
                else if (ans[j]==4) printf("west\n");
            }
            return;
        }
    }
}
int main()
{
    int ret=0;
    while (scanf("%d",&n)!=EOF)
    {
        if (ret++) printf("\n");
        work();
    }
    return 0;    
}