Movie Weekend Codechef Beginner Section : Runtime Error - c++

Question

I have written the following code for the problem, ideone doesnt give me runtime error but the compiler for codechef is giving me one. The compiler in codechef is gcc 4.9.2
Problem [Link : https://www.codechef.com/problems/MOVIEWKN]
Little Egor is a huge movie fan. He likes watching different kinds of movies: from drama movies to comedy movies, from teen movies to horror movies. He is planning to visit cinema this weekend, but he's not sure which movie he should watch.
There are n movies to watch during this weekend. Each movie can be characterized by two integers Li and Ri, denoting the length and the rating of the corresponding movie. Egor wants to watch exactly one movie with the maximal value of Li × Ri. If there are several such movies, he would pick a one with the maximal Ri among them. If there is still a tie, he would pick the one with the minimal index among them.
Your task is to help Egor to pick a movie to watch during this weekend.
Expected Input
The first line of the input contains an integer T denoting the number of test cases.
The first line of the test case description contains an integer n(number of films).
The second line of the test case description contains n integers L1, L2, ...,Ln (L is the Length of the movie). The following line contains n integers R1, R2, ..., Rn(R is the Rating of the movie).
My Input
2
2
1 2
2 1
4
2 1 4 1
2 4 1 4
Expected Output
For each test case, output a single integer i denoting the index of the movie. Note that 1-based indexing is followed.
My Output
1
2
Explanation
In the first example case, both films have the same value of L × R, but the first film has a better rating.
In the second example case, the second and the fourth movies are equally good, but the second movie has a smaller index
My Solution
#include<iostream>
#include<string>
#include<vector>
using namespace std;
int main() {
int T;
cin >> T;
cin.ignore();
if (T >= 1 && T <= 5) {
for (int q = 0; q < T; q++) {
int n;
size_t pos;
cin >> n;
cin.ignore();
if (n >= 1 && n <= 100) {
vector<int> L;
vector<int> R;
vector<int> C;
for (int u = 0; u < n; u++) {
int a;
cin >> a;
cin.ignore();
if (a >= 1 && a <= 100) {
L.push_back(a);
}
}
for (int u = 0; u < n; u++) {
int a;
cin >> a;
cin.ignore();
if (a >= 1 && a <= 100) {
R.push_back(a);
}
}
for (int u = 0; u < n; u++) {
int df = (L[u] * R[u]);
C.push_back(df);
}
for (size_t u = 0; u < C.size(); u++) {
int max = C[0];
if (max < C[u]) {
max = C[u];
pos = u+1;
}
if (max == C[u]) {
if (R[pos-1] < R[u]) { pos = u + 1; }
if (R[pos - 1] == R[u]) {
if (pos > u) { pos = u + 1; }
}
}
}
cout << pos << endl;
}
}
}
return 0;
}
After going through some of the questions on runtime error regarding codechef questions, i am guessing the problem is related to accessing an out of boundary element but i am not able to pinpoint the actual problem

Answer 1

In this line:
if (R[pos - 1] < R[u]) { pos = u + 1; }
The first time around the loop, pos is uninitialised, leading to undefined behaviour.
Simple fix:
add pos = 1 before the loop

Answer 2

I'm probably late but here is my simple solution:
t=int(input())
for j in range(0,t):
n=int(input())
a=[int(ele) for ele in input().split()]
b=[int(ele) for ele in input().split()]
c=[]
pos=0
max=-1
max2=-1
for i in range(0,n):
fl=0
c.append(a[i]*b[i])
if(max<c[i]):
max=c[i]
fl=1
if(fl==1):
pos=i+1
max2=b[i]
elif(max==c[i]):
if(max2<b[i]):
pos=i+1
max2=b[i]
print(pos)