How can I remove the segmentation error in the following code? - c++11

Question

In the following code, I am getting the segmentation fault. Whenever the query type is 1, we have to push element into the stack, if it is 2 then we have to pop from stack, and if it is 3 then print the maximum value in the stack.
My guess is that the error is present somewhere in the switch case. However, I am unable to spot it. Please help.
#include<bits/stdc++.h>
using namespace std;
int maxinStack(stack<int> st){
int max=st.top();
for (int i=0;i<st.size();i++){
if(st.top()>max){
max=st.top();
}
st.pop();
}
return max;
}
int main() {
/* Enter your code here. Read input from STDIN. Print output to STDOUT */
stack<int> s;
int querySize;
cin >> querySize;
vector<int> queryType(querySize);
queue<int> queryData;
for(int i=0;i<querySize;i++){
cin>>queryType[i];
if(queryType[i]==1){
int x;
cin >> x;
queryData.push(x);
}
}
/*for (int j=0;j<querySize;j++){
cout << queryType.at(j)<<" ";
}
cout << endl;
while(!queryData.empty()){
cout << queryData.front()<<" ";
queryData.pop();
}
cout << endl;
*/
for (int j=0;j<querySize;j++){
switch (queryType[j]){
case 1:{
int y=queryData.front();
s.push(y);
queryData.pop();
}
case 2: s.pop();
case 3: cout << maxinStack(s)<<endl;
}
}
return 0;
}

Answer 1

Assuming inputs are correct, I think you forgot to put break at the end of each case handlers.
So it should be something like:
switch (queryType[j]){
case 1:{
int y=queryData.front();
s.push(y);
queryData.pop();
break;
}
case 2: s.pop(); break;
case 3: cout << maxinStack(s)<<endl; break;
}
Otherwise when it handles case 1 it will still fall-through to the next case handlers so it also does case 2 and case 3. This means that the stack is always empty and it causes segmentation fault when it handles query type of 2 - tried to pop for an empty stack.

Answer 2

As pointed above by #Hanjoung, your switch cases are missing break statements. Just to give you a little context on these break statements, if not specified all the cases after the matched case will also run. For eg:
switch(choice){
case 1:
case 2: // Suppose this case matched
case 3: // This will also run as no break in case 2
break;
case 4: // Will not run as break in case 3
default:
}
The reason you are getting segmentation error is because your "case 2" is popping from empty stack, and reason for running of this "case 2" is absence of break statement in "case 1".