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source/solver.c

 /* solver.c */
-/* Last Change: 2018/08/26 (Sun) 05:44:44. */
+/* Last Change: 2018/08/26 (Sun) 14:46:21. */
 
 #define MAX_ATTEMPS 1000000
 
@@ -12,13 +12,13 @@
 
 int board[8][72][72]={};
 int avail[8][72][72]={}; //start=3,path=2,avail=1,nonavail=0,goal=-1
-int connected[8*72*72/2+1]={};
+int connected[8*72*72/2+1]={}; //connected[0]=(number of connected lines)
 int depth,height,width;
 int lines;
-int searchorder[6];
+int searchorder[6]; //x+-,y+-,z+-
 //z,y,x
 
-void read(void){
+void read(void){ //read problem
 	int x,y,z,i;
 	char c,str[8];
 	scanf(" %s",str); //SIZE
@@ -73,11 +73,11 @@ void read(void){
 	return;
 }
 
-int randline(void){ //1-lines -> 1-lines
+int randline(void){ //return random line number
 	return rand()%lines+1;
 }
 
-int available(int startx,int starty, int startz){
+int available(int startx,int starty, int startz){ //return 1 when (startx,starty,startz) can be connected to goal
 	if(avail[startz][starty][startx]==-1) //goal
 		return 1;
 	if(avail[startz][starty][startx]==2||avail[startz][starty][startx]==3) //visited
@@ -114,7 +114,7 @@ int available(int startx,int starty, int startz){
 	return 0;
 }
 
-int connectable(int linea,int lineb){
+int connectable(int linea,int lineb){ //return 1 if linea canbe connected when lineb is deleted
 	int startx=-1,starty=-1,startz=-1,notfound=1;
 	int i,j,k;
 	for(i=0;i<depth;i++)
@@ -129,30 +129,31 @@ int connectable(int linea,int lineb){
 						avail[startz][starty][startx]=3;
 					}else{
 						avail[i][j][k]=-1; //goal
+						notfound=2;
 					}
 				}else if(board[i][j][k]==0||board[i][j][k]==lineb||board[i][j][k]==linea){
 					avail[i][j][k]=1;
 				}else{
 					avail[i][j][k]=0;
 				}
-	if(startx==-1||starty==-1||startz==-1){
+	if(startx==-1||starty==-1||startz==-1||notfound!=2){
 		printf("Error: Line %d\n",linea);
 		return 0;
 	}
 	return available(startx,starty,startz);
 }
 
-void connect(int num){
+void connect(int line){ //connect line
 	int i,j,k;
 	for(i=0;i<depth;i++)
 		for(j=0;j<height;j++)
 			for(k=0;k<width;k++)
 				if(avail[i][j][k]==2&&board[i][j][k]==0)
-					board[i][j][k]=num;
+					board[i][j][k]=line;
 	return;
 }
 
-void delete(int line){
+void delete(int line){ //delete line
 	int i,j,k;
 	for(i=0;i<depth;i++)
 		for(j=0;j<height;j++)
@@ -164,11 +165,11 @@ void delete(int line){
 
 int solve(void){ //return 1 when solved, 0 when cannot
 	int i,j,linea,lineb;
-	for(i=0;i<MAX_ATTEMPS;i++){
+	for(i=0;i<MAX_ATTEMPS;i++){ //try to connect MAX_ATTEMPS times
 		linea=randline();
 		if(connected[linea])
 			continue;
-		if(connectable(linea,0)){
+		if(connectable(linea,0)){ //if linea canbe conneced without deleting lines
 			connect(linea);
 			connected[linea]=1;
 			connected[0]++;
@@ -176,7 +177,7 @@ int solve(void){ //return 1 when solved, 0 when cannot
 				return 1;
 		}
 		else{
-			for(j=0;j<MAX_ATTEMPS;j++){
+			for(j=0;j<MAX_ATTEMPS;j++){ //try to find a line to delete
 				lineb=randline();
 				if(connectable(linea,lineb)){
 					delete(lineb);