source/solver.c

 /* solver.c */
-/* Last Change: 2018/08/26 (Sun) 23:31:34. */
+/* Last Change: 2018/08/27 (Mon) 23:42:09. */
 
-#define MAX_ATTEMPS 100000
+#define MAX_ATTEMPS 10000
 
 #include<stdio.h>
 #include<stdlib.h>
@@ -16,6 +16,11 @@ int connected[8*72*72/2+1]={}; //connected[0]=(number of connected lines)
 int depth,height,width;
 int goalx,goaly,goalz;
 int lines;
+int dx[6]={-1,0,0,1,0,0};
+int dy[6]={0,-1,0,0,1,0};
+int dz[6]={0,0,-1,0,0,1};
+int history[8*72*72];
+int searchorder[6]; //x+-,y+-,z+-
 //z,y,x
 
 void read(void){ //read problem
@@ -73,28 +78,27 @@ void read(void){ //read problem
 	return;
 }
 
-int randline(void){ //return random line number
-	return rand()%lines+1;
-}
-
-void shuffle(int array[],int start,int end){
-	int i,j,t;
-	if(end==start)
-		return;
-	for(i=start;i<end;i++){
-		j=start+rand()%(end-start);
-		t=array[i];
-		array[i]=array[j];
-		array[j]=t;
+int available(int z,int y, int x){ //return 1 when (nowx,nowy,nowz) can be connected to goal
+	int i,j,t,src=0,contd,isbranch;
+	int index=0;
+	int nowx=x,nowy=y,nowz=z;
+	/* for(i=0;i<6;i++) */
+	/* printf("%d %d %d\n",dx[i],dy[i],dz[i]); */
+	for(i=0;i<8*72*72;i++)
+		history[i]=-1;
+	index=0;
+	while(1){
+		/* printf("%d %d %d\n",nowx,nowy,nowz); */
+		if(nowx<0||nowy<0||nowz<0||nowx>=width||nowy>=height||nowz>=depth){
+			printf("error %d %d %d\n",nowx,nowy,nowz);
+			/* printf("%d, %d\n",index,history[index]); */
+			/* printf("%d %d %d\n",dx[history[index]],dy[history[index]],dz[history[index]]); */
+			return 0;
 		}
-}
-
-int available(int nowx,int nowy, int nowz,int flag){ //return 1 when (nowx,nowy,nowz) can be connected to goal
-	if(avail[nowz][nowy][nowx]==-1) //goal
+		if(avail[nowz][nowy][nowx]==-1){ //goal
 			return 1;
-	if(avail[nowz][nowy][nowx]!=1&&flag==0)
-		return 0;
-	int isbranch=-1;
+		}
+		isbranch=-1;
 		if(nowx>0&&avail[nowz][nowy][nowx-1]>=2)
 			isbranch++;
 		if(nowy>0&&avail[nowz][nowy-1][nowx]>=2)
@@ -107,16 +111,27 @@ int available(int nowx,int nowy, int nowz,int flag){ //return 1 when (nowx,nowy,
 			isbranch++;
 		if(nowz<depth-1&&avail[nowz+1][nowy][nowx]>=2)
 			isbranch++;
-	if(isbranch>0){
+		if(isbranch>0&&index){
+			avail[nowz][nowy][nowx]=0;
+			index--;
+			if(nowx-dx[history[index]]<0||nowy-dy[history[index]]<0||nowz-dx[history[index]]<0||nowx-dz[history[index]]>=width||nowy-dy[history[index]]>=height||nowz-dz[history[index]]>=depth){
+				index++;
+				/* printf("something wrong\n"); */
+			}else{
+				nowx-=dx[history[index]];
+				nowy-=dy[history[index]];
+				nowz-=dz[history[index]];
 				avail[nowz][nowy][nowx]=1;
-		return 0;
+				/* printf("%d %d %d -%d %d\n",nowx,nowy,nowz,history[index],index); */
+				/* for(j=0;j<index;j++) */
+				/* 	printf("%d ",history[j]); */
+				/* printf("\n"); */
+				/* return 0;//goback */
+				continue;
+			}
 		}
 		if(avail[nowz][nowy][nowx]==1)
 			avail[nowz][nowy][nowx]=2;
-	int i,src=0;
-	int searchorder[6]; //x+-,y+-,z+-
-	/* for(i=0;i<6;i++) */
-	/* searchorder[i]=-1; */
 		if(nowx>goalx){
 			searchorder[src]=0;
 			src++;
@@ -147,9 +162,6 @@ int available(int nowx,int nowy, int nowz,int flag){ //return 1 when (nowx,nowy,
 			src++;
 		}else
 			searchorder[src]=5;
-	/* shuffle(searchorder,0,src); */
-	/* shuffle(searchorder,src,6); */
-	int j,t;
 		for(i=0;i<src;i++){
 			j=rand()%(src);
 			t=searchorder[i];
@@ -162,40 +174,47 @@ int available(int nowx,int nowy, int nowz,int flag){ //return 1 when (nowx,nowy,
 			searchorder[i]=searchorder[j];
 			searchorder[j]=t;
 		}
-	/* for(i=0;i<6;i++) */
-	/* 	printf("%d ",searchorder[i]); */
+		contd=1;
+		for(i=0;i<6&&contd;i++){
+			/* printf("%d\n",searchorder[i]); */
+			if(nowx+dx[searchorder[i]]<0||nowy+dy[searchorder[i]]<0||nowz+dx[searchorder[i]]<0||nowx+dz[searchorder[i]]>=width||nowy+dy[searchorder[i]]>=height||nowz+dz[searchorder[i]]>=depth)
+				continue;
+			if(avail[nowz+dz[searchorder[i]]][nowy+dy[searchorder[i]]][nowx+dx[searchorder[i]]]==1){
+				contd=0;
+				nowx+=dx[searchorder[i]];
+				nowy+=dy[searchorder[i]];
+				nowz+=dz[searchorder[i]];
+				/* printf("%d %d %d\n",dx[searchorder[i]],dy[searchorder[i]],dz[searchorder[i]]); */
+				history[index]=searchorder[i];
+				/* printf("%d %d %d +%d %d\n",nowx,nowy,nowz,searchorder[i],index+1); */
+				/* for(j=0;j<index;j++) */
+				/* 	printf("%d ",history[j]); */
 				/* printf("\n"); */
-	for(i=0;i<6;i++)
-		switch(searchorder[i]){
-			case 0:
-				if(nowx>0&&available(nowx-1,nowy,nowz,0))
-					return 1;
-				break;
-			case 1:
-				if(nowy>0&&available(nowx,nowy-1,nowz,0))
-					return 1;
-				break;
-			case 2:
-				if(nowz>0&&available(nowx,nowy,nowz-1,0))
-					return 1;
-				break;
-			case 3:
-				if(nowx<width-1&&available(nowx+1,nowy,nowz,0))
-					return 1;
-				break;
-			case 4:
-				if(nowy<height-1&&available(nowx,nowy+1,nowz,0))
-					return 1;
-				break;
-			case 5:
-				if(nowz<depth-1&&available(nowx,nowy,nowz+1,0))
-					return 1;
-				break;
-			default:
-				break;
+				index++;
 			}
-	if(avail[nowz][nowy][nowx]==2)
+		}
+		if(avail[nowz][nowy][nowx]==3||index==0)
+			return 0;
+		if(contd&&index){
+			avail[nowz][nowy][nowx]=0;
+			index--;
+			if(nowx-dx[history[index]]<0||nowy-dy[history[index]]<0||nowz-dx[history[index]]<0||nowx-dz[history[index]]>=width||nowy-dy[history[index]]>=height||nowz-dz[history[index]]>=depth){
+				index++;
+				/* printf("something wrong\n"); */
+			}else{
+				nowx-=dx[history[index]];
+				nowy-=dy[history[index]];
+				nowz-=dz[history[index]];
 				avail[nowz][nowy][nowx]=1;
+				/* printf("%d %d %d -%d %d\n",nowx,nowy,nowz,history[index],index); */
+				/* for(j=0;j<index;j++) */
+				/* 	printf("%d ",history[j]); */
+				/* printf("\n"); */
+				/* printf("%d %d %d\n",dx[history[index]],dy[history[index]],dz[history[index]]); */
+				continue;
+			}
+		}
+	}
 	return 0;
 }
 
@@ -228,7 +247,7 @@ int connectable(int linea,int lineb){ //return 1 if linea can be connected when
 		printf("Error: Line %d\n",linea);
 		return 0;
 	}
-	return available(startx,starty,startz,1);
+	return available(startz,starty,startx);
 }
 
 void connect(int line){ //connect line
@@ -256,9 +275,9 @@ void delete(int line){ //delete line
 }
 
 int solve(void){ //return 1 when solved, 0 when cannot
-	int i,j,linea,lineb;
+	int i,linea,lineb[10000];
 	for(i=0;i<MAX_ATTEMPS;i++){ //try to connect MAX_ATTEMPS times
-		linea=randline();
+		linea=rand()%lines+1;
 		if(connected[linea])
 			continue;
 		if(connectable(linea,0)){ //if linea canbe conneced without deleting lines
@@ -267,22 +286,31 @@ int solve(void){ //return 1 when solved, 0 when cannot
 			connected[0]++;
 			if(connected[0]==lines)
 				return 1;
+		}else{
+			int j,t;
+			for(i=0;i<lines;i++){
+				lineb[i]=i+1;
 			}
-		else{
-			for(j=0;j<MAX_ATTEMPS;j++){ //try to find a line to delete
-				lineb=randline();
-				if(connectable(linea,lineb)){
-					delete(lineb);
+			for(i=0;i<lines;i++){ //shuffle
+				j=rand()%(lines);
+				t=lineb[i];
+				lineb[i]=lineb[j];
+				lineb[j]=t;
+			}
+			for(i=0;i<lines;i++){
+				if(connectable(linea,lineb[i])){
+					delete(lineb[i]);
 					connect(linea);
 					connected[linea]=1;
-					connected[lineb]=0;
+					connected[lineb[i]]=0;
 					break;
 				}
-				if(j==MAX_ATTEMPS-1)
+				if(j==MAX_ATTEMPS-1){
 					return 0;
 				}
 			}
 		}
+	}
 	return 0;
 }