A*启发式搜索

来源：互联网发布：一键上传淘宝的危害编辑：程序博客网时间：2024/05/21 17:54

转自：http://blog.csdn.net/sxy_cnyali/article/details/50951326

#include<bits/stdc++.h>#define REP(i,j,k) for (int i=(j);i<=(k);++i)#define abs(x) ((x)>0?(x):-(x))using namespace std;const int maxn=1010,dmax=maxn*maxn,INF=0x3f3f3f3f,d[5][2]={{0,0},{1,0},{0,1},{-1,0},{0,-1}};int a[maxn][maxn],f[maxn][maxn],n,m,sx,sy,ex,ey;bool p[maxn][maxn];struct node{int x,y,w;node(){x=y=w=0;}};struct node pre[maxn][maxn],s;int value(node h){ return h.w+abs(h.x-ex)+abs(h.y-ey); }struct heap{struct node q[dmax];int t=0;public:void push(node x){q[++t]=x;int k=t;while (k>1 && q[k].w<q[k/2].w){swap(q[k],q[k/2]);k/=2;}}void pop(){if (t==0) return;q[1]=q[t--];int k=1;while ((k*2<=t && q[k].w>q[k*2].w) || (k*2+1<=t && q[k].w>q[k*2+1].w)){int m=k*2;if (m+1<=t && q[m].w>q[m+1].w) ++m;swap(q[k],q[m]);k=m;}}node top(){ return q[1]; }};heap q;int main(){int ans=-1;scanf("%d%d",&n,&m);REP(i,1,n)REP(j,1,m)scanf("%d",&a[i][j]);scanf("%d%d%d%d",&sx,&sy,&ex,&ey);if (sx==ex && sy==ey){puts("0");return 0;}bool flag=1;node tmp;tmp.x=sx;tmp.y=sy;tmp.w=0;pre[sx][sy]=tmp;q.push(tmp);do{node h=q.top();q.pop();p[h.x][h.y]=1;REP(i,1,4){int x=h.x+d[i][0],y=h.y+d[i][1];node t;t.x=x;t.y=y;t.w=h.w+1;if (a[x][y] || p[x][y] || x<1 || y<1 || x>n || y>m) continue;if (f[x][y]==0 || f[x][y]>value(t)){f[x][y]=value(t);pre[x][y]=t;p[x][y]=1;if (x==ex && y==ey){s=t;ans=h.w+1;flag=0;break;}q.push(t);}}}while (flag);printf("%d\n",ans);return 0;}

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