Your task is to rotate given matrix on 90 degree counterclockwise.

Question

What is wrong?

#include <iostream>

using namespace std;

int main() {
int a[100][100];
int n,m;
cin>>n>>m;
for(int i=0;i<n;i++){
for(int j=0;j<m;j++){
cin>>a[i][j];
}
}
for(int j=0;j<m;j++){
for(int i=n-1;i>=0;i--){
cout<<a[i][j];

}cout<<endl;
}
return 0;
}

Answer 1

Example
Input
1 2 3
4 5 6
7 8 9
Your Output
7 4 1
8 5 2
9 6 3
Expected Output
3 6 9
2 5 8
1 4 7
The problem is
for(int j=0;j<m;j++){
for(int i=n-1;i>=0;i--){
cout<<a[i][j];
}cout<<endl;
}
Correct one
for(int j=m-1;j>=0;--j){
for(int i=0;i<n;++i){
cout<<a[i][j]<<" ";
}cout<<endl;
}
Just try to dry run your code first, most of the time we find the flaw during that phase, I hope this helps.