PROBLEM LINK:
Contest Division 1
Contest Division 2
Contest Division 3
Practice
Setter: Bharat Singla
Tester: Felipe Mota
Editorialist: Aman Dwivedi
DIFFICULTY
Cakewalk
PREREQUISITES
None
PROBLEM:
You are given a string S. Your task is to find whether the given string S is a valid closing HTML tag or not.
A closing HTML tag must:
- Start with "</"
- End with ">"
- Have only, and at least 1, lower-case alpha-numeric characters as its body
Help Chef by printing Success if the tag is fine. If not, print Error.
QUICK EXPLANATION:
We have a string S, and our goal is to find whether the given string is a valid HTML tag or not. Let us check the condition one by one:
Case 1: It should Start with "</"
-
It means that the first character of the given string should be < while the second character of this string should be /.
-
If the starting two characters of string S fulfill the requirement, we will move to check another condition otherwise the string is not valid.
Case 2: It should end with ">"
-
It means that the last character of the given string should be >.
-
If the requirement is fulfilled we move to check the last condition left otherwise the string is not valid.
Case 3: Have only, and at least 1, lower-case alphanumeric characters as its body
-
It means the remaining characters of the string S should contain only lowercase English alphabets ora digit and there should be at least one such character in the body.
-
We can simply iterate on the remaining string and can check this condition.
If all the conditions are full-filled then the string S is considered to be valid otherwise not.
TIME COMPLEXITY:
O(|S|) per test case
SOLUTIONS:
Setter
#include <bits/stdc++.h>
using namespace std;
void solve() {
string s;
cin >> s;
int n = s.length();
if (n < 4 or s.substr(0, 2) != "</" or s[n-1] != '>') {
cout << "Error\n";
return;
}
bool is_valid = true;
for (int i = 2; i < n - 1; i++) {
bool is_alpha = (s[i] >= 'a' and s[i] <= 'z');
bool is_num = (s[i] >= '0' and s[i] <= '9');
if (!is_alpha and !is_num) {
is_valid = false;
break;
}
}
cout << (is_valid ? "Success" : "Error") << endl;
}
int main() {
int tc;
cin >> tc;
while (tc--) solve();
return 0;
}
Tester
#include <bits/stdc++.h>
using namespace std;
template<typename T = int> vector<T> create(size_t n){ return vector<T>(n); }
template<typename T, typename... Args> auto create(size_t n, Args... args){ return vector<decltype(create<T>(args...))>(n, create<T>(args...)); }
long long readInt(long long l,long long r,char endd){
long long x=0;
int cnt=0;
int fi=-1;
bool is_neg=false;
while(true){
char g=getchar();
if(g=='-'){
assert(fi==-1);
is_neg=true;
continue;
}
if('0'<=g && g<='9'){
x*=10;
x+=g-'0';
if(cnt==0){
fi=g-'0';
}
cnt++;
assert(fi!=0 || cnt==1);
assert(fi!=0 || is_neg==false);
assert(!(cnt>19 || ( cnt==19 && fi>1) ));
} else if(g==endd){
if(is_neg){
x= -x;
}
assert(l<=x && x<=r);
return x;
} else {
assert(false);
}
}
}
string readString(int l,int r,char endd){
string ret="";
int cnt=0;
while(true){
char g=getchar();
assert(g!=-1);
if(g==endd){
break;
}
cnt++;
ret+=g;
}
assert(l<=cnt && cnt<=r);
return ret;
}
long long readIntSp(long long l,long long r){
return readInt(l,r,' ');
}
long long readIntLn(long long l,long long r){
return readInt(l,r,'\n');
}
string readStringLn(int l,int r){
return readString(l,r,'\n');
}
string readStringSp(int l,int r){
return readString(l,r,' ');
}
int main(){
ios::sync_with_stdio(false);
cin.tie(0);
int t = readIntLn(1, 1000);
while(t--){
string s = readStringLn(1, 1000);
for(auto c : s){
assert(33 <= c && c <= 126);
}
if(s.size() > 3){
bool ok = s[0] == '<' && s[1] == '/' && s[s.size() - 1] == '>';
for(int i = 2; i + 1 < s.size(); i++)
if(islower(s[i]) || isdigit(s[i]));
else ok = false;
cout << (ok ? "Success\n" : "Error\n");
} else {
cout << "Error\n";
}
}
return 0;
}
Editorialist
##include<bits/stdc++.h>
using namespace std;
#define int long long
void solve()
{
bool ok = true;
string s;
cin>>s;
int n=(int)s.size();
if(n<4)
{
cout<<"Error"<<"\n";
return;
}
if(s[0]!='<' || s[1]!='/' || s[n-1]!='>')
ok=false;
if(ok)
{
for(int i=2;i<n-1;i++)
{
if(!((s[i]>='a' && s[i]<='z') ||
(s[i]>='0' && s[i]<='9')))
{
ok=false;
break;
}
}
}
if(ok)
cout<<"Success"<<"\n";
else
cout<<"Error"<<"\n";
}
int32_t main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
int t;
cin>>t;
while(t--)
solve();
return 0;
}
