diff --git a/ZOJ/3945_csdn.cpp b/ZOJ/3945_csdn.cpp
new file mode 100644
index 0000000..0f14ee3
--- /dev/null
+++ b/ZOJ/3945_csdn.cpp
@@ -0,0 +1,491 @@
+#include<bits/stdc++.h>
+
+using namespace std;
+
+struct Pt{
+	double x, y, z;
+} A,B,C,D;
+
+const double eps = 1e-8;
+const double _5 = sqrt(5.0);
+const double _2 = sqrt(2.0);
+double f[3];
+
+typedef pair<Pt, Pt> PPP;
+
+struct Pi{
+	int x, y, z;
+};
+
+bool operator < (const Pi & a, const Pi & b){
+	return (a.x < b.x);
+}
+
+bool operator == (const Pi & a, const Pi & b){
+	return (a.x == b.x && a.y == b.y && a.z == b.z);
+}
+
+void Pit(const Pt & X){
+	cout<<X.x<<' '<<X.y<<' '<<X.z<<endl;
+}
+
+bool operator == (const Pt & a, const Pt & b){
+	return (fabs(a.x - b.x) < eps && fabs(a.y - b.y) < eps && fabs(a.z - b.z) < eps);
+}
+
+Pt work(Pt X, int k){
+	return (Pt){X.x - 0.5 + (k & 1), X.y - 0.5 + ((k >> 1) & 1), X.z - 0.5 + ((k >> 2) & 1)};
+}
+
+/******************************/
+
+#ifdef SPFA
+	#define MAXD 60
+#else
+	#define MAXD 30
+#endif
+
+bool dis2_inRange(int x, int y, int z){
+	return 0 <= x && x <= MAXD && 0 <= y && y <= MAXD && 0 <= z && z <= MAXD;
+}
+
+inline double dis2_getDis(int cnt){
+	return cnt > 3 ? 1E100 : cnt == 3 ? _5 : cnt == 2 ? _2 : 1.0;
+}
+
+int dis2_getDis(int x, int y, int z, int ux, int uy, int uz){
+	const int t = -2;
+	if (((x | 1) != (ux | 1) || (y | 1) != (uy | 1) || (z | 1) != (uz | 1))
+		&& ((x + (x & 1)) != (ux + (ux & 1)) || (y + (y & 1)) != (uy + (uy & 1)) || (z + (z & 1)) != (uz + (uz & 1))))
+		return 4;
+	return (x != ux) + (y != uy) + (z != uz);
+}
+
+void dis2_pre(Pi st, double (&dis)[MAXD + 1][MAXD + 1][MAXD + 1], int (&dt)[MAXD + 1][MAXD + 1][MAXD + 1][3]){
+	static bool in[MAXD + 1][MAXD + 1][MAXD + 1];
+	for (int i = 0; i <= MAXD; ++i)
+		for (int j = 0; j <= MAXD; ++j)
+			for (int k = 0; k <= MAXD; ++k){
+				dis[i][j][k] = 1E100;
+				in[i][j][k] = false;
+				dt[i][j][k][0] = dt[i][j][k][1] = dt[i][j][k][2] = 0;
+			}
+	dis[st.x][st.y][st.z] = 0;
+	queue<Pi> Q;
+	Q.push(st);
+	while (!Q.empty()){
+		Pi u = Q.front();
+		Q.pop();
+//		fprintf(stderr, "start update: %d %d %d\n", u.x, u.y, u.z);
+		for (int i = -1; i <= 1; ++i)
+			for (int j = -1; j <= 1; ++j)
+				for (int k = -1; k <= 1; ++k){
+					int x = u.x + i, y = u.y + j, z = u.z + k;
+					if (dis2_inRange(x, y, z)){
+						int tmp = dis2_getDis(u.x, u.y, u.z, x, y, z);
+						if (dis[x][y][z] > dis[u.x][u.y][u.z] + dis2_getDis(tmp)){
+							dis[x][y][z] = dis[u.x][u.y][u.z] + dis2_getDis(tmp);
+							dt[x][y][z][0] = dt[u.x][u.y][u.z][0];
+							dt[x][y][z][1] = dt[u.x][u.y][u.z][1];
+							dt[x][y][z][2] = dt[u.x][u.y][u.z][2];
+							++dt[x][y][z][tmp - 1];
+//							printf("%d %d %d\n", x, y, z);
+							if (!in[x][y][z]){
+//								puts("- =");
+								in[x][y][z] = true;
+								Q.push((Pi){x, y, z});
+							}
+						}
+					}
+				}
+		in[u.x][u.y][u.z] = false;
+	}
+}
+
+double dis2(Pi st, Pi ed){
+	static bool used = false;
+	static double dis[8][MAXD + 1][MAXD + 1][MAXD + 1];
+	static int dt[8][MAXD + 1][MAXD + 1][MAXD + 1][3];
+
+	/* prework */
+	if (!used){
+		used = true;
+		for (int i = 0; i < 8; ++i)
+			dis2_pre((Pi){i >> 2 & 1, i >> 1 & 1, i & 1}, dis[i], dt[i]);
+	}
+
+	int dx = ed.x - st.x, dy = ed.y - st.y, dz = ed.z - st.z;
+
+	if (dx < dy){
+		swap(dx, dy);
+		swap(st.x, st.y);
+		swap(ed.x, ed.y);
+	}
+	if (dx < dz){
+		swap(dx, dz);
+		swap(st.x, st.z);
+		swap(ed.x, ed.z);
+	}
+	if (dy < dz){
+		swap(dy, dz);
+		swap(st.y, st.z);
+		swap(ed.y, ed.z);
+	}
+
+	int cnt2 = 0, cnt1 = 0;
+#ifndef SPFA
+	int Maki = 5;
+	int tx = max(0, dx - Maki) & -4, ty = max(0, dy - Maki) & -4, tz = max(0, dz - Maki) & -4;
+//	printf("%d %d %d\n", tx, ty, tz);
+	dx -= tx, dy -= ty, dz -= tz;
+	if (ty + tz <= tx){
+		tx -= cnt2 = ty + tz;
+		cnt1 += max(0, tx - dy - dz);
+		dx += min(dy + dz, tx);
+	}
+	else
+		cnt2 += tx + ty + tz >> 1;
+//	printf("- %d %d %d, %d %d\n", dx, dy, dz, cnt1, cnt2);
+//	printf("st: %d %d %d\n", st.x, st.y, st.z);
+#endif
+	ed.x = st.x + dx;
+	ed.y = st.y + dy;
+	ed.z = st.z + dz;
+	int type = st.x << 2 | st.y << 1 | st.z;
+//	printf("%d %d %d\n", cnt1 + dt[type][ed.x][ed.y][ed.z][0], cnt2 + dt[type][ed.x][ed.y][ed.z][1], dt[type][ed.x][ed.y][ed.z][2]);
+	return cnt1 + cnt2 * _2 + dis[type][ed.x][ed.y][ed.z];
+}
+
+#undef MAXD
+
+/******************************/
+
+double _dis2(Pt P, Pt Q){
+	f[0] = fabs(P.x - Q.x);
+	f[1] = fabs(P.y - Q.y);
+	f[2] = fabs(P.z - Q.z);
+	sort(f, f + 3);
+	f[2] -= f[1];
+	f[1] -= f[0];
+	return _5 * f[0] + _2 * f[1] + f[2];
+}
+
+Pt operator -(const Pt & a, const Pt & b){
+	return (Pt){a.x - b.x, a.y - b.y, a.z - b.z};
+}
+
+Pt operator +(const Pt & a, const Pt & b){
+	return (Pt){a.x + b.x, a.y + b.y, a.z + b.z};
+}
+
+Pt operator *(const Pt & a, double x){
+	return (Pt){a.x * x, a.y * x, a.z * x};
+}
+
+double sqr(double x){
+	return x * x;
+}
+
+inline double len(const Pt & a){
+	return sqrt(sqr(a.x)+sqr(a.y)+sqr(a.z));
+}
+
+double dg(double x, double y){
+	return sqrt(sqr(x) + sqr(y));
+}
+
+PPP a[100];
+
+int like(double p, double q, double r){
+	if (fabs(p - q) < eps && fabs(q - r) < eps)
+		return 1;
+	else
+		return 0;
+}
+
+double le[100][100];
+
+double Get_s(Pt p, Pt q){
+	for(int i = 0; i < 12; i++)
+		for(int j = 0; j < 12; j++){
+			if (like(a[i].first.x, a[j].first.x, 0) || like(a[i].first.x, a[j].first.x, 1))
+				le[i][j] = len(a[i].first - a[j].first);
+			else if (like(a[i].first.y, a[j].first.y, 0) || like(a[i].first.y, a[j].first.y, 1))
+				le[i][j] = len(a[i].first - a[j].first);
+			else if (like(a[i].first.z, a[j].first.z, 0) || like(a[i].first.z, a[j].first.z, 1))
+				le[i][j] = len(a[i].first - a[j].first);
+			else
+				le[i][j] = 12345678;
+		}
+	for(int i = 0; i < 12; i++){
+		if (like(a[i].first.x, p.x, 0) ||like(a[i].first.x, p.x, 1) ||
+			like(a[i].first.y, p.y, 0) ||like(a[i].first.y, p.y, 1) ||
+			like(a[i].first.z, p.z, 0) ||like(a[i].first.z, p.z, 1))
+			le[i][13] = le[13][i] = len(p - a[i].first);
+		else
+			le[i][13] = le[13][i] = 12345678;
+		if (like(a[i].first.x, q.x, 0) ||like(a[i].first.x, q.x, 1) ||
+			like(a[i].first.y, q.y, 0) ||like(a[i].first.y, q.y, 1) ||
+			like(a[i].first.z, q.z, 0) ||like(a[i].first.z, q.z, 1))
+			le[i][12] = le[12][i] = len(q - a[i].first);
+		else
+			le[i][12] = le[12][i] = 12345678;
+	}
+	le[13][13] = le[12][12] = 0;
+	if (like(p.x, q.x, 0) || like(p.y, q.y, 0) || like(p.z, q.z, 0) || like(p.x, q.x, 1) || like(p.y, q.y, 1) || like(p.z, q.z, 1))
+		le[13][12] = le[12][13] = len(p - q);
+	else
+		le[13][12] = le[12][13] = 12345678;
+	for(int k = 0; k < 14; k++)
+		for(int i = 0; i < 14; i++)
+			for(int j = 0; j < 14; j++)
+				le[i][j] = min(le[i][j] , le[i][k] + le[k][j]);
+	return le[12][13];
+}
+
+double tf(Pt p, Pt q){
+	for(int i = 0; i <= 1; i++)
+		for(int j = 0; j <= 1; j++)
+			a[(i << 1) + j + 0] = (PPP){(Pt){i, j, rand()/(double)(RAND_MAX)}, (Pt){0, 0, 1}};
+	for(int i = 0; i <= 1; i++)
+		for(int j = 0; j <= 1; j++)
+			a[(i << 1) + j + 4] = (PPP){(Pt){i, rand()/(double)(RAND_MAX), j}, (Pt){0, 1, 0}};
+	for(int i = 0; i <= 1; i++)
+		for(int j = 0; j <= 1; j++)
+			a[(i << 1) + j + 8] = (PPP){(Pt){rand()/(double)(RAND_MAX), i, j}, (Pt){1, 0, 0}};
+	double now = Get_s(p, q);
+	double t = 0.5;
+	while(t > 0.001){
+		int flag = 0;
+		for(int i = 0; i < 12; i++)
+			if (!flag){
+				a[20] = a[i];
+				a[i].first = a[i].first + (a[i].second * t);
+				double tmp = Get_s(p, q);
+				if (tmp < now){
+					flag = 1;
+					while(tmp < now){
+						now = tmp;
+						a[20] = a[i];
+						a[i].first = a[i].first + (a[i].second * t);
+						tmp = Get_s(p, q);
+					}
+				}
+				a[i] = a[20];
+			}
+		t *= 0.9;
+	}
+	return now;
+}
+
+double dis1(Pt P, Pt Q, Pt R){
+//	puts("QAQ");
+	P = P - R;
+	Q = Q - R;
+	P.x += 0.5, P.y += 0.5, P.z += 0.5;
+	Q.x += 0.5, Q.y += 0.5, Q.z += 0.5;
+//	Pit(P), Pit(Q);
+	double ans = 10;
+	for(int ts = 0; ts < 100; ts++){
+//		puts("= -");
+		ans = min(ans, tf(P, Q));
+	}
+//	cout<<"tf:\t"<<ans<<endl;
+	return ans;
+}
+
+double _dis1(Pt P, Pt Q, Pt R){
+//	puts("#############################");
+/*	Pit(P);
+	Pit(Q);
+	Pit(R);
+*/	P = P - R;
+	Q = Q - R;
+/*	Pit(P);
+	Pit(Q);
+*/	if (fabs(fabs(P.x) - 0.5) > eps){
+		if (fabs(fabs(P.y) - 0.5) <= eps){
+			swap(P.y, P.x);
+			swap(Q.y, Q.x);
+		}
+		else{
+			swap(P.z, P.x);
+			swap(Q.z, Q.x);
+		}
+	}
+	if (fabs(P.x + 0.5) < eps){
+		P.x = -P.x, Q.x = -Q.x;
+	}
+	if (fabs(Q.x - 0.5) < eps){//On the same face
+	//	cout<<"tl:\t"<<sqrt(sqr(P.y - Q.y) + sqr(P.z - Q.z))<<endl;
+		return sqrt(sqr(P.y - Q.y) + sqr(P.z - Q.z));
+	}
+	if (fabs(fabs(Q.y) - 0.5) < eps || fabs(fabs(Q.z) - 0.5) < eps){//have a common edge
+		if (fabs(fabs(Q.y) - 0.5) > eps){
+			swap(Q.y, Q.z);
+			swap(P.y, P.z);
+		}
+		if (fabs(Q.y + 0.5) < eps){
+			Q.y = -Q.y, P.y = -P.y;
+		}
+	//	cout<<"tl:\t"<<min(dg(1-P.y-Q.x, P.z-Q.z), min(dg(1-P.y-Q.z, 1-P.z-Q.x), dg(1+P.z-Q.x,1+Q.z-P.y)))<<endl;
+		return min(dg(1-P.y-Q.x, P.z-Q.z), min(dg(1-P.y-Q.z, 1-P.z-Q.x), dg(1+P.z-Q.x,1+Q.z-P.y)));
+	}
+	//On the opposite face
+	double sum = 12345678;
+	//passing another face
+	sum = min(sum , dg(2 - P.z - Q.z, P.y - Q.y));
+	sum = min(sum , dg(2 + P.z + Q.z, P.y - Q.y));
+	sum = min(sum , dg(2 + P.y + Q.y, P.z - Q.z));
+	sum = min(sum , dg(2 - P.y - Q.y, P.z - Q.z));
+	//passing two other faces
+	sum = min(sum, dg(2 - P.y - Q.z, 1 - P.z - Q.y));
+	sum = min(sum, dg(2 - P.y + Q.z, 1 + P.z - Q.y));
+	sum = min(sum, dg(2 + P.y - Q.z, 1 - P.z + Q.y));
+	sum = min(sum, dg(2 + P.y + Q.z, 1 + P.z + Q.y));
+	sum = min(sum, dg(2 + P.z + Q.y, 1 + P.y + Q.z));
+	sum = min(sum, dg(2 + P.z - Q.y, 1 - P.y + Q.z));
+	sum = min(sum, dg(2 - P.z + Q.y, 1 + P.y - Q.z));
+	sum = min(sum, dg(2 - P.z - Q.y, 1 - P.y - Q.z));
+//	cout<<"tl:\t"<<sum<<endl;
+	return sum;
+}
+
+Pt getcenter(Pt X){
+	int x, y, z;
+	x = (int)(round(X.x));
+	y = (int)(round(X.y));
+	z = (int)(round(X.z));
+	if (fabs(fabs(fmod(X.x, 1)) - 0.5) > eps){
+		if ((y & 1) != (x & 1)){
+			y = (int)(round(X.y * 2 - y));
+		}
+		if ((z & 1) != (x & 1)){
+			z = (int)(round(X.z * 2 - z));
+		}
+	}
+	else{
+		if (fabs(fabs(fmod(X.y, 1)) - 0.5) > eps){
+			if ((y & 1) != (x & 1)){
+				x = (int)(round(X.x * 2 - x));
+			}
+			if ((z & 1) != (y & 1)){
+				z = (int)(round(X.z * 2 - z));
+			}
+		}
+		else{
+			if ((z & 1) != (x & 1)){
+				x = (int)(round(X.x * 2 - x));
+			}
+			if ((z & 1) != (y & 1)){
+				y = (int)(round(X.y * 2 - y));
+			}
+		}
+	}
+	return (Pt){(double)x, (double)y, (double)z};
+}
+
+double Nico(Pt P, Pt Q){
+	Pi p = (Pi){(int)(round(P.x + 0.5)), (int)(round(P.y + 0.5)), (int)(round(P.z + 0.5))};
+	Pi q = (Pi){(int)(round(Q.x + 0.5)), (int)(round(Q.y + 0.5)), (int)(round(Q.z + 0.5))};
+	q.x -= (p.x / 2) * 2, p.x -= (p.x / 2) * 2;
+	if (p.x == -1){q.x += 2, p.x += 2;}
+	q.y -= (p.y / 2) * 2, p.y -= (p.y / 2) * 2;
+	if (p.y == -1){q.y += 2, p.y += 2;}
+	q.z -= (p.z / 2) * 2, p.z -= (p.z / 2) * 2;
+	if (p.z == -1){q.z += 2, p.z += 2;}
+	if (q.x <= 0){
+		q.x = 1 - q.x;
+		p.x = 1 - p.x;
+	}
+	if (q.y <= 0){
+		q.y = 1 - q.y;
+		p.y = 1 - p.y;
+	}
+	if (q.z <= 0){
+		q.z = 1 - q.z;
+		p.z = 1 - p.z;
+	}
+	return dis2(p, q);
+}
+
+void ck(double x){
+	assert(x >= -9999  && x <= 9999);
+}
+
+int main(){
+//	freopen("J.in", "r", stdin);
+//	freopen("J.out", "w", stdout);
+//
+
+	srand(time(NULL));
+	int T;
+	scanf("%d",&T);
+
+/*
+	for(int i = 0; i < 100;  i++){
+		scanf("%lf%lf%lf", &A.x, &A.y, &A.z);
+		scanf("%lf%lf%lf", &B.x, &B.y, &B.z);
+		dis1(A, B, (Pt){0, 0, 0});
+		_dis1(A, B, (Pt){0, 0, 0});
+	}
+	return 0;
+*/
+	while(T--){
+		scanf("%lf%lf%lf", &A.x, &A.y, &A.z);
+		scanf("%lf%lf%lf", &B.x, &B.y, &B.z);
+		ck(A.x); ck(A.y); ck(A.z);
+		ck(B.x); ck(B.y); ck(B.z);
+		C = getcenter(A);
+		assert((A.x - C.x - eps) <= 0.5 && (A.x - C.x + eps) >= -0.5);
+		assert((A.y - C.y - eps) <= 0.5 && (A.y - C.y + eps) >= -0.5);
+		assert((A.z - C.z - eps) <= 0.5 && (A.z - C.z + eps) >= -0.5);
+		assert(((int)round(C.x - C.y)) % 2 == 0);
+		assert(((int)round(C.x - C.z)) % 2 == 0);
+		D = getcenter(B);
+		assert((B.x - D.x - eps) <= 0.5 && (B.x - D.x + eps) >= -0.5);
+		assert((B.y - D.y - eps) <= 0.5 && (B.y - D.y + eps) >= -0.5);
+		assert((B.z - D.z - eps) <= 0.5 && (B.z - D.z + eps) >= -0.5);
+		assert(((int)round(D.x - D.y)) % 2 == 0);
+		assert(((int)round(D.x - D.z)) % 2 == 0);
+		double ans = 1234567;
+		if (C == D){
+			ans = _dis1(A, B, C);
+		}
+		else{
+			
+			for(int i = 0; i < 8; i++)
+				for(int j = 0; j < 8; j++){
+				//	ans = min(ans,dis2(work(C, i), work(D, j)));
+				//	dis1(A, work(C, i), C);
+				//	_dis1(A, work(C, i), C);
+				//	dis1(B, work(D, j), D);
+				//	_dis1(B, work(D, j), D);
+					ans = min(ans, _dis1(A, work(C, i), C) + _dis1(B, work(D, j), D) + Nico(work(C, i), work(D, j)));
+				//	ans = min(ans, dis1(A, work(C, i), C) + dis1(B, work(D, j), D) + dis2(work(C, i), work(D, j)));
+				}
+		}
+		printf("%.16f\n", ans);
+	}
+	return 0;
+}
+ 
+
+/*
+0.733017 0.493771 1
+0.429134 0 0.88777
+tf:	0.678462
+tl:	0.677924
+0.25458 0 1
+0.165501 1 0.459615
+tf:	1.4132
+tl:	1.4108
+0.561626 0 0
+1 0.0775424 0.207269
+tf:	0.556202
+tl:	0.555994
+0 0.98381 1
+1 0.962809 0.831134
+tf:	1.06045
+tl:	1.05357
+*/