delete pics to save space

history_source/ccf 基础篇/U2/2.4.1.cpp

@@ -0,0 +1,18 @@
+#include<iostream>
+#include<string>
+using namespace std;
+bool pan(string sr)
+{
+	if(!((sr[0]>='a'&&sr[0]<='z')||(sr[0]>='A'&&sr[0]<='Z')||sr[0]=='_')) return 0;
+	for(int i=0;i<sr.size();i++) if(!((sr[i]>='a'&&sr[i]<='z')||(sr[i]>='A'&&sr[i]<='Z')||sr[i]=='_'||(sr[i]>='0'&&sr[i]<='9'))) return 0;
+	return 1;
+}
+int main()
+{
+	string sr;
+	getline(cin,sr);
+	if(pan(sr)) cout<<"yes";
+	else cout<<"no";
+	cout<<endl;
+	return 0;
+}