delete pics to save space

2.12657.cpp

@@ -0,0 +1,58 @@
+#include<cstdio>
+#include<algorithm>
+using namespace std;
+const int maxn=100005;
+int left[maxn],right[maxn];
+int n,m,kase;
+inline int link(int a,int b)
+{
+	right[a]=b;
+	left[b]=a;
+}
+int main()
+{
+#ifdef local
+	freopen("pro.in","r",stdin);
+#endif
+	while(scanf("%d%d",&n,&m)==2)
+	{
+		for(int i=1;i<=n;i++)
+		{
+			left[i]=i-1;
+			right[i]=(i+1)%(n+1);
+		}
+		right[0]=1;left[0]=n;
+		int op,X,Y,inv=0;
+		while(m-->0)
+		{
+			scanf("%d",&op);
+			if(op==4) inv=!inv;
+			else
+			{
+				scanf("%d%d",&X,&Y);
+				if(op==3&&right[Y]==X) swap(X,Y);
+				if(op!=3&&inv) op=3-op;
+				if(op==1&&X==left[Y]) continue;
+				if(op==2&&X==right[Y]) continue;
+				int LX=left[X],RX=right[X],LY=left[Y],RY=right[Y];
+				if(op==1) link(LX,RX),link(LY,X),link(X,Y);
+				if(op==2) link(LX,RX),link(Y,X),link(X,RY);
+				if(op==3)
+				{
+					if(right[X]==Y) link(LX,Y),link(Y,X),link(X,RY);
+					else link(LX,Y),link(Y,RX),link(LY,X),link(X,RY);
+				}
+			}
+		}
+		int b=0;
+		long long ans=0;
+		for(int i=1;i<=n;i++)
+		{
+			b=right[b];
+			if(i&1) ans+=b;
+		}
+		if(inv&&!(n&1)) ans=(long long)n*(n+1)/2-ans;
+		printf("Case %d: %lld\n",++kase,ans);
+	}
+	return 0;
+}