Error in the Array

Question

I am a 10th grade student have just started competitive programming. I was recently was solving this.

While trying to solve this question I encountered this error.

prog.cpp:32:43: error: invalid types ‘[int*]’ for array subscript std::swap(a[p], *std::min_element[b,b+n]); ^ I tried to find a solution but have been stuck on this problem for almost a day.

This is my code:

#include <iostream>
#include <list>
#include <algorithm>
#include <functional>
#include <bits/stdc++.h>
using namespace std;
int main(){
 int n,k,a[100005]={0},b[100005]={0};
 cin>>n>>k;
 for(int i=0;i<n;i++)
 cin>>a[i];
 for(int i=0;i<n;i++)
 cin>>b[i];
 sort(a,a+n);
 sort(b,b+n);
 int one = 0, two = 0, p = n - 1, j = n - 1;
 for ( k>=0;k--) {
 if(k==0){
 cout<<*std::max_element(a,a+n)+*std::min_element(b,b+n)<< "\n";
 }
 if (a[p]>b[j]) {
 std::swap(b[j], *std::min_element[a,a+n]);
 j--;
 one++;
 }
 if (a[p]<b[j]) {
 std::swap(a[p], *std::min_element[b,b+n]);
 p--;
 two++;
 }
 }
 return (0);
}

I would really appreciate if som eone would tell me what I am doing wrong. Also, please point out to anyways I can make my code better.

• Abhijith Chadnran: I will certainly read it Sir. But I would really appreciate if you point to the specific mistake in my code.
• acraig5075: min_element is a function so call it with parenthesis () not square brackets []
• acraig5075: Your for (k >= 0; k--) loop looks suspect too...
• Useless: You shouldn't include `<bits/stdc++.h>, it's an internal implementation detail of the (some) standard library implementations.

Answer 1

To improve your coding style, I suggest reading the linux kernel coding style document. Although it's not meant for C++, it can still be applied here.

Concerning the code itself, it feels like your getting ahead of yourself. I've cleaned it up a bit. It compiles with g++.

#include <iostream>
#include <list>
#include <algorithm>
#include <functional>
#include <bits/stdc++.h>
using namespace std;
int main(){
 int n,k,a[100005]={0},b[100005]={0};
 cin>>n>>k;
 for(int i=0;i<n;i++){
 cin>>a[i];
 }
 for(int i=0;i<n;i++){
 cin>>b[i];
 }
 sort(a,a+n);
 sort(b,b+n);
 int one = 0, two = 0, p = n - 1, j = n - 1;
 for (;k>=0;k--) {
 if(k==0){
 cout<<*max_element(a,a+n)+*min_element(b,b+n)<< "\n";
 }
 if (a[p]>b[j]) {
 swap(b[j], *min_element(a,a+n));
 j--;
 one++;
 }
 if (a[p]<b[j]) {
 swap(a[p], *min_element(b,b+n));
 p--;
 }
 }
 return 0;
}

Here's an overview of the things I changed:

1. Used scoping '{}' to improve readability. It makes it much more clear what code is executed within a loop or if/else statement.
2. Used tabs and spaces consistently throughout your snippet of code.
3. Used the statement 'using namespace std;'. This basically means that everything within the standard library can be addressed without 'std::' in front of it. Hence 'std::swap()' becomes 'swap()' and so on. Do note that this is considered bad practice. Read the following on scopes and namespaces to understand them better.
4. Changed the for loop to 'for(;k>=0;k--)'.A for loop typically has three items separated by semi-colons within the parenthesis. Item 1 is the initialization, you're not using it here. Item 2 is the condition to check, here 'k>=0'. Item 3 is the increment. Read this for more information. You can leave all three items blank (creating an infinite loop), but the two semi-colons need to be there.

• Abhijith Chadnran: Thank You @Bruno Hendrickx, for such an informative answer. Will definitely look forward to all the improvements that you have suggested