delete pics to save space

7.1733.cpp

@@ -0,0 +1,55 @@
+#include<cstdio>
+#include<algorithm>
+using namespace std;
+struct { int l,r,ans; } query[10010];
+int n,m,fa[20010],d[20010],a[20010],cnt;
+inline int ff(int u)
+{
+	int a=u,b,c=0;
+	while(u!=fa[u]) c^=d[u],u=fa[u];
+	while(a!=u)
+	{
+		b=fa[a];
+		c^=d[a];
+		d[a]^=c;
+		fa[a]=u;
+		a=b;
+	}
+	return u;
+}
+int main()
+{
+#ifdef local
+	freopen("pro.in","r",stdin);
+#endif
+	scanf("%d%d",&n,&m);
+	for(int i=1;i<=m;i++)
+	{
+		char s[10]; scanf("%d%d%s",&query[i].l,&query[i].r,s);
+		query[i].ans=(s[0]=='o');
+		a[++cnt]=query[i].l-1; a[++cnt]=query[i].r;
+	}
+	sort(a+1,a+1+cnt); n=unique(a+1,a+1+cnt)-(a+1);
+	for(int i=1;i<=n;i++) fa[i]=i;
+	for(int i=1;i<=m;i++)
+	{
+		int x=lower_bound(a+1,a+1+n,query[i].l-1)-a;
+		int y=lower_bound(a+1,a+1+n,query[i].r)-a;
+		int p=ff(x),q=ff(y);
+		if(p==q)
+		{
+			if((d[x]^d[y])!=query[i].ans)
+			{
+				printf("%d\n",i-1);
+				return 0;
+			}
+		}
+		else
+		{
+			fa[p]=q;
+			d[p]=d[x]^d[y]^query[i].ans;
+		}
+	}
+	printf("%d\n",m);
+	return 0;
+}