UVa 11212 Editing a Book

黑书P207 例题

IDA* 搜索，估价函数设计得很经典。

#include <iostream>
#include <cstdio>
#include <cstring>
using namespace std;
class Board
{
public:
    int a[16];
    int h;
    int n;
    bool readIn()
    {
        int i;
        scanf("%d",&n);
        if (n == 0)
            return false;
        for (i=0; i<n; i++)
        {
            scanf("%d",a+i);
        }
        return true;
    }
    void printOut()
    {
        int i;
        for (i=0; i<n; i++)
        {
            printf("%d ", a[i]);
        }
        printf("\n");
        printf("h=%d\n",h);
    }
    void move(int s,int e,int p)
    {
        int t[16],i,j;
        if (p < s)
        {
            for (i=0; i<p; i++)
            {
                t[i]=a[i];
            }
            for (j=s; j<=e; j++,i++)
            {
                t[i]=a[j];
            }
            for (j=p; j<s; j++,i++)
            {
                t[i]=a[j];
            }
            for (j=e+1; j<n; j++,i++)
            {
                t[i]=a[j];
            }
        }
        else
        {
            for (i=0; i<s; i++)
            {
                t[i]=a[i];
            }
            for (j=e+1; j<p; j++,i++)
            {
                t[i]=a[j];
            }
            for (j=s; j<=e; j++,i++)
            {
                t[i]=a[j];
            }
            for (j=p; j<n; j++,i++)
            {
                t[i]=a[j];
            }
        }
        memcpy(a,t,sizeof(t));
    }
    int getH()
    {
        int cnt,i;
        cnt=0;
        for (i=0; i<n-1; i++)
        {
            if (a[i+1] != a[i]+1)
              cnt++;
        }
        if (a[i] != n)
            cnt++;
        h=cnt;
        return cnt;
    }
};
int lim;
int f(int dep,int h)
{
    return dep*3+h;
}
bool IDDFS(int dep,Board b)
{
    int i,j,k;
    Board tb;
    b.getH();
   /* printf("%d %d\n",dep,lim);
    b.printOut();
    getchar();
*/
    if (f(dep,b.h) > lim*3)
        return false;
    if (b.getH() == 0)
        return true;
    for (i=0; i<b.n; i++)
    {
        for (j=i; j<b.n; j++)
        {
            for (k=0; k<i; k++)
            {
                tb=b;
                tb.move(i,j,k);
                if (IDDFS(dep+1,tb) == true)
                    return true;
            }
            for (k=j+2; k<b.n; k++)
            {
                tb=b;
                tb.move(i,j,k);
                if (IDDFS(dep+1,tb) == true)
                    return true;
            }
        }
    }
    return false;
}
int main()
{
    Board b;
    int prob;
    prob=1;
    while (b.readIn() == true)
    {
        for (lim=0; ; lim++)
        {
            if (IDDFS(0,b) == true)
                break;
        }
        printf("Case %d: %d\n",prob,lim);
        prob++;
    }
}