diff --git a/hls_2018/README.md b/hls_2018/README.md
index f11e0eff8440e2eb403991c267609980da74e7e0..063636aa3acc070e23c3ec01f073734be1827987 100644
--- a/hls_2018/README.md
+++ b/hls_2018/README.md
@@ -10,6 +10,7 @@ PYNQ-router for Vivado-HLS (2018 ver.)
 |02|TBD|*Line-number-free* router for "PYNQ-Z1". Priority queue is implemented with circular array(parallel)|
 |03|TBD|*Line-number-free* router for "PYNQ-Z1". Priority queue is implemented with heap(size:$`2^{15}`$)|
 |04|TBD|*Line-number-free* router for "AVNET-Ultra96". Priority queue is implemented with heap(size:$`2^{16}`$)|
+|05|TBD|*Low-memory-usage* router. No BRAMs are used for storing route information of each line.|
 
 ## Memo
 
diff --git a/hls_2018/router_05/solver.c b/hls_2018/router_05/solver.c
new file mode 100644
index 0000000000000000000000000000000000000000..ba77daa34bb0df7b5f97419b431463dbfb1fd3ff
--- /dev/null
+++ b/hls_2018/router_05/solver.c
@@ -0,0 +1,317 @@
+/* solver.c */
+/* Last Change: 2018/08/26 (Sun) 23:31:34. */
+
+#define MAX_ATTEMPS 100000
+
+#include<stdio.h>
+#include<stdlib.h>
+#include<string.h>
+/* #include<limits.h> */
+/* #include<math.h> */
+#include<time.h>
+
+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]={}; //connected[0]=(number of connected lines)
+int depth,height,width;
+int goalx,goaly,goalz;
+int lines;
+//z,y,x
+
+void read(void){ //read problem
+	int x,y,z,i;
+	char c,str[8];
+	scanf(" %s",str); //SIZE
+	scanf(" %d",&width);
+	if(width>72||width<=0)
+		printf("Error: width\n");
+	scanf(" %c",&c); //X
+	scanf(" %d",&height);
+	if(height>72||height<=0)
+		printf("Error: height\n");
+	scanf(" %c",&c); //X
+	scanf(" %d",&depth);
+	if(depth>8||depth<=0)
+		printf("Error: depth\n");
+	scanf(" %s",str); //LINE_NUM
+	scanf(" %d",&lines);
+	if(lines<=0)
+		printf("Error: lines\n");
+	for(i=1;i<=lines;i++){
+		scanf(" %s",str); //LINE#X
+		scanf(" %c",&c); //(
+		scanf(" %d",&x);
+		if(x>=72||x<0)
+			printf("Error: x\n");
+		scanf(" %c",&c); //,
+		scanf(" %d",&y);
+		if(y>=72||y<0)
+			printf("Error: y\n");
+		scanf(" %c",&c); //,
+		scanf(" %d",&z);
+		if(z>=72||z<0)
+			printf("Error: z\n");
+		scanf(" %c",&c); //)
+		board[z-1][y][x]=-i;
+		scanf("%c",&c); //)
+		/* scanf(" %[ -]",&c); //space or - */
+		scanf(" %c",&c); //(
+		scanf(" %d",&x);
+		if(x>=72||x<0)
+			printf("Error: x\n");
+		scanf(" %c",&c); //,
+		scanf(" %d",&y);
+		if(y>=72||y<0)
+			printf("Error: y\n");
+		scanf(" %c",&c); //,
+		scanf(" %d",&z);
+		if(z>=72||z<0)
+			printf("Error: z\n");
+		scanf(" %c",&c); //)
+		board[z-1][y][x]=-i;
+	}
+	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 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
+		return 1;
+	if(avail[nowz][nowy][nowx]!=1&&flag==0)
+		return 0;
+	int isbranch=-1;
+	if(nowx>0&&avail[nowz][nowy][nowx-1]>=2)
+		isbranch++;
+	if(nowy>0&&avail[nowz][nowy-1][nowx]>=2)
+		isbranch++;
+	if(nowz>0&&avail[nowz-1][nowy][nowx]>=2)
+		isbranch++;
+	if(nowx<width-1&&avail[nowz][nowy][nowx+1]>=2)
+		isbranch++;
+	if(nowy<height-1&&avail[nowz][nowy+1][nowx]>=2)
+		isbranch++;
+	if(nowz<depth-1&&avail[nowz+1][nowy][nowx]>=2)
+		isbranch++;
+	if(isbranch>0){
+		avail[nowz][nowy][nowx]=1;
+		return 0;
+	}
+	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++;
+	}else
+		searchorder[5+src]=0;
+	if(nowy>goaly){
+		searchorder[src]=1;
+		src++;
+	}else
+		searchorder[4+src]=1;
+	if(nowz>goalz){
+		searchorder[src]=2;
+		src++;
+	}else
+		searchorder[3+src]=2;
+	if(nowx<goalx){
+		searchorder[src]=3;
+		src++;
+	}else
+		searchorder[2+src]=3;
+	if(nowy<goaly){
+		searchorder[src]=4;
+		src++;
+	}else
+		searchorder[1+src]=4;
+	if(nowz<goalz){
+		searchorder[src]=5;
+		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];
+		searchorder[i]=searchorder[j];
+		searchorder[j]=t;
+	}
+	for(i=src;i<6;i++){
+		j=src+rand()%(6-src);
+		t=searchorder[i];
+		searchorder[i]=searchorder[j];
+		searchorder[j]=t;
+	}
+	/* for(i=0;i<6;i++) */
+	/* 	printf("%d ",searchorder[i]); */
+	/* 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;
+		}
+	if(avail[nowz][nowy][nowx]==2)
+		avail[nowz][nowy][nowx]=1;
+	return 0;
+}
+
+int connectable(int linea,int lineb){ //return 1 if linea can be connected when lineb is deleted
+	int startx=-1,starty=-1,startz=-1,notfound=1;
+	int i,j,k;
+	for(i=0;i<depth;i++)
+		for(j=0;j<height;j++)
+			for(k=0;k<width;k++)
+				if(board[i][j][k]==linea*(-1)){
+					if(notfound){ //start
+						startz=i;
+						starty=j;
+						startx=k;
+						avail[i][j][k]=3;
+						notfound=0;
+					}else{ //goal
+						goalz=i;
+						goaly=j;
+						goalx=k;
+						avail[i][j][k]=-1;
+						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||notfound!=2){
+		printf("Error: Line %d\n",linea);
+		return 0;
+	}
+	return available(startx,starty,startz,1);
+}
+
+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){
+					if(board[i][j][k]==0)
+						board[i][j][k]=line;
+					else
+						printf("something wrong");
+				}
+	return;
+}
+
+void delete(int line){ //delete line
+	int i,j,k;
+	for(i=0;i<depth;i++)
+		for(j=0;j<height;j++)
+			for(k=0;k<width;k++)
+				if(board[i][j][k]==line)
+					board[i][j][k]=0;
+	return;
+}
+
+int solve(void){ //return 1 when solved, 0 when cannot
+	int i,j,linea,lineb;
+	for(i=0;i<MAX_ATTEMPS;i++){ //try to connect MAX_ATTEMPS times
+		linea=randline();
+		if(connected[linea])
+			continue;
+		if(connectable(linea,0)){ //if linea canbe conneced without deleting lines
+			connect(linea);
+			connected[linea]=1;
+			connected[0]++;
+			if(connected[0]==lines)
+				return 1;
+		}
+		else{
+			for(j=0;j<MAX_ATTEMPS;j++){ //try to find a line to delete
+				lineb=randline();
+				if(connectable(linea,lineb)){
+					delete(lineb);
+					connect(linea);
+					connected[linea]=1;
+					connected[lineb]=0;
+					break;
+				}
+				if(j==MAX_ATTEMPS-1)
+					return 0;
+			}
+		}
+	}
+	return 0;
+}
+
+void write(void){
+	int i,j,k;
+	printf("SIZE %dX%dX%d\n",width,height,depth);
+	for(k=0;k<depth;k++){
+		printf("LAYER %d\n",k+1);
+		for(j=0;j<height;j++){
+			for(i=0;i<width-1;i++){
+				if(board[k][j][i]<0)
+					board[k][j][i]=-board[k][j][i];
+				printf("%d, ",board[k][j][i]);
+			}
+			if(board[k][j][i]<0)
+				board[k][j][i]=-board[k][j][i];
+			printf("%d",board[k][j][i]);
+			printf("\n");
+		}
+	}
+	return;
+}
+
+int main(void){
+	srand((unsigned)time(NULL));
+	read();
+	if(solve())
+		write();
+	else
+		printf("Cannot solve!\n");
+	return 0;
+}