Printing Triangles: Top-Left, Bottom-Left, Top-Right, Bottom-Right

These were some examples my programming teacher used when teaching loops in class. I think the problems themselves aren't hard, but they're great for practicing loops and training your reaction speed. Also, my VB skills have gotten a lot rusty... So I'm attaching the C++ code for everyone to look at. Go study it yourselves～

The problem is the one in the image at the top: use only loops to produce the four triangles shown above. The solution is below.

Code:

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#include 
#include <math.h>
using namespace std;
int main()
{
int x=5;
cout«“三角形一："«endl;
for(int i=1;i<=x;i++){
for(int y=1;y<=i;y++){
cout«”";
}
cout«endl;
}
cout«endl;
cout«“三角形二："«endl;
for(int i=x;i>=1;i–){
for(int y=1;y<=i;y++){
cout«”";
}
cout«endl;
}
cout«endl;
cout«“三角形三："«endl;
for(int i=1;i<=x;i++){
for(int y=x;y>i;y–){
cout«” “;
}
for(int y=1;y<=i;y++){
cout«”*";
}
    cout<<endl;
}
cout<<endl;
cout<<"三角形四："<<endl;
for(int i=1;i<=x;i++){
    for(int y=1;y<i;y++){
        cout<<" ";
    }
    for(int y=x;y>=i;y--){
        cout<<"*";
    }

    cout<<endl;
}
return 0;
}