delete pics to save space

7.1945.cpp

@@ -0,0 +1,53 @@
+#include<cstdio>
+#include<queue>
+#include<set>
+#include<algorithm>
+using namespace std;
+const int P=50005;
+struct Data
+{
+	int a,b,s,f;
+	Data() { }
+	Data(int _a,int _b,int _s,int _f):a(_a),b(_b),s(_s),f(_f) { }
+};
+inline bool operator<(const Data &a,const Data &b) { return a.s+a.f>b.s+b.f; }
+priority_queue<Data> Q;
+set<int> vis;
+int n; Data u;
+inline int gcd(int a,int b) { return b?gcd(b,a%b):a; }
+inline void Ext(int a,int b)
+{
+	if(a==0&&b==0) return;
+	if(a<b) swap(a,b);
+	if(b>170) return;
+	if(a>2*n) return;
+	if(b==0&&a>n) return;
+	if(n%gcd(a,b)) return;
+	if(vis.find(a*P+b)!=vis.end()) return;
+	int h=0,t=a;
+	while(t<n) t<<=1,h++;
+	Q.push(Data(a,b,u.s+1,h));
+//	printf("push %d %d %d %d\n",a,b,u.s+1,h);
+}
+int main()
+{
+#ifdef local
+	freopen("pro.in","r",stdin);
+//	freopen("pro.out","w",stdout);
+#endif
+	scanf("%d",&n);
+	Q.push(Data(1,0,0,0));
+	while(Q.size())
+	{
+		u=Q.top(); Q.pop();
+		if(vis.find(u.a*P+u.b)!=vis.end()) continue;
+//		printf("dis[%d,%d]=%d\n",u.a,u.b,u.s);
+		if(u.a==n) { printf("%d\n",u.s); return 0; }
+		vis.insert(u.a*P+u.b);
+		Ext(u.a+u.a,u.b); Ext(u.a,u.a+u.a);
+		Ext(u.b+u.b,u.b); Ext(u.a,u.b+u.b);
+		Ext(u.a+u.b,u.b); Ext(u.a,u.a+u.b);
+		Ext(u.a-u.b,u.b); Ext(u.a,u.a-u.b);
+	}
+	return 0;
+}