Help in HELPTECH (Code Mantra)

help
, ,
6

@admin add these problems to practice please…, i can’t see a submit(practice) button there yet

7

same. I don’t believe that my logic was perfectly sound. Instead, i think that its a weak testcase since my code didn’t give output in the expected order for sample testcase

8

Can anyone find the mistake in this code?
It is giving SIGSEGV upon executing.

#include<bits/stdc++.h> 
#define ll long long int
#define endl '\n'
#define MOD 1000000007;
using namespace std;
struct student{
    string name;
    string phone;
    int marks;
    int order;
};
bool mysort(student &a,student &b){
    if(a.marks == b.marks)
        return a.order < b.order;
    return a.marks < b.marks;
}
int main(){
ios_base :: sync_with_stdio(0);
cin.tie(0);
cout.tie(0);	
ll tt;
cin >> tt;
while(tt--){
    int n;  
    cin >> n;
    vector<student> arr(n);
    string sname,number;
    int m;
    ll total = 0;
    for(int i = 0;i < n;i++){
        cin >> n >> number >> m;
        arr[i].name = sname;
        arr[i].phone = number;
        arr[i].marks = m;
        arr[i].order = i;
        total += m;
    }
    sort(arr.begin(),arr.end(),mysort);
    for(int i = 0;i < n;i++){
        if(arr[i].marks * n < total)
            cout << arr[i].name << " " << arr[i].phone << " " << arr[i].marks << endl;
    }

}
return 0;
}
9

You have taken n as input instead of sname

10

A silly mistake can cost you 100 points!
Thanks btw.

11

Here key is string, It should be converted to int

12

Not sorted as per increasing order of marks

13

how do we sort it? is there an editorial?

14

Also,when will the problems be added to the practice section?

15

Editorial should be avialble by today.

You can have a look here

T = int(input())
for z in range(T):
    N = int(input())
    details = []
    for i in range(N):
        name, phone, marks = input().split()
        details.append((name, phone, int(marks)))
    # Find sum of marks
    total = sum(elem[2] for elem in details)
    avg = total / N

    details.sort(key=lambda x: x[2])  # Sort by score
    for student in details:
        if student[2] < avg:
            print(student[0], student[1], student[2])
1 Like
16

When will they open CodeMantra for Practice.

17

but why i am getting sorted output then?

18

^^ @admin

19

had i known this statement, I could have solved the problem

20

You can store them in a tuple and use bubble sort here which is O(n^2). It should easily pass.

1 Like
21

if anyone wants a c++ code…

#include<bits/stdc++.h>
using namespace std;
typedef long long int ll;

int main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
ll t,n;
cin>>t;
while(t–)
{
cin>>n;
string s;
ll ph[n],marks[n];
float sum=0;
vector<pair<string,ll>>v;
for(int i=0;i<n;i++)
{
cin>>s>>ph[i]>>marks[i];
v.push_back(make_pair(s,marks[i]));
sum+=marks[i];
}
sum=sum/(double)n;
sort(marks,marks+n);
for(int i=0;i<n;i++)
{
if(marks[i]<sum)
{
for(int j=0;j<n;j++)
{
if(v[j].second==marks[i])
{
cout<<v[j].first<<" “<<ph[j]<<” "<<v[j].second<<endl;
v[j].second=-1;
}
}
}
}
}
return 0;
}

22

You are getting sorted output by string.
Because you are not converting them to int before sorting.
For example,

final = [ ['baban','1234567890','44'] ,['abhichal','9876543210','5'] ]
ans=sorted(final,key=itemgetter(2))

Then ans = [ [‘abhichal’,‘9876543210’,‘44’], [‘baban’,‘1234567890’,‘5’]]. Because 44 is alphabetically smaller then 5.

However, if you write

ans=sorted(final,key=int(itemgetter(2)))

You will get it correctly.

23

ohk got it

24

would be nice if you format your codes… (use ``` for basics or visit the discuss page)

25

thanks : )