1. Như gợi ý của bạn Alt+F4. Mình xin gửi chương trình mình viết đơn giản, bạn thêm mắm muối vô cho đẹp 
Mã:
#include<conio.h>
#include<stdio.h>
void main()
{
int a;
clrscr();
printf("Nhap a");scanf("%d",&a);
if (a%2==0)
printf("So chan");
else
printf("So le");
getch();
}
2. Tham khảo đoạn code này, từ đó bạn dễ dàng suy ra thuật toán cho riêng bạn
Mã:
[COLOR=#000000][COLOR=#FF8000]#include<conio.h>
#include<stdio.h>
[/COLOR][COLOR=#0000BB]int main[/COLOR][COLOR=#007700]()
{
[/COLOR][COLOR=#0000BB]float a[/COLOR][COLOR=#007700],[/COLOR][COLOR=#0000BB]b[/COLOR][COLOR=#007700],[/COLOR][COLOR=#0000BB]c[/COLOR][COLOR=#007700];
[/COLOR][COLOR=#0000BB]printf[/COLOR][COLOR=#007700]([/COLOR][COLOR=#DD0000]"Nhap cac canh cua tam giac\n"[/COLOR][COLOR=#007700]);
[/COLOR][COLOR=#0000BB]printf[/COLOR][COLOR=#007700]([/COLOR][COLOR=#DD0000]"a= "[/COLOR][COLOR=#007700]);
[/COLOR][COLOR=#0000BB]scanf[/COLOR][COLOR=#007700]([/COLOR][COLOR=#DD0000]"%f"[/COLOR][COLOR=#007700],&[/COLOR][COLOR=#0000BB]a[/COLOR][COLOR=#007700]);
[/COLOR][COLOR=#0000BB]printf[/COLOR][COLOR=#007700]([/COLOR][COLOR=#DD0000]"b= "[/COLOR][COLOR=#007700]);
[/COLOR][COLOR=#0000BB]scanf[/COLOR][COLOR=#007700]([/COLOR][COLOR=#DD0000]"%f"[/COLOR][COLOR=#007700],&[/COLOR][COLOR=#0000BB]b[/COLOR][COLOR=#007700]);
[/COLOR][COLOR=#0000BB]printf[/COLOR][COLOR=#007700]([/COLOR][COLOR=#DD0000]"c= "[/COLOR][COLOR=#007700]);
[/COLOR][COLOR=#0000BB]scanf[/COLOR][COLOR=#007700]([/COLOR][COLOR=#DD0000]"%f"[/COLOR][COLOR=#007700],&[/COLOR][COLOR=#0000BB]c[/COLOR][COLOR=#007700]);
if (([/COLOR][COLOR=#0000BB]a[/COLOR][COLOR=#007700]+[/COLOR][COLOR=#0000BB]b[/COLOR][COLOR=#007700]>=[/COLOR][COLOR=#0000BB]c[/COLOR][COLOR=#007700])&&([/COLOR][COLOR=#0000BB]b[/COLOR][COLOR=#007700]+[/COLOR][COLOR=#0000BB]c[/COLOR][COLOR=#007700]>=[/COLOR][COLOR=#0000BB]a[/COLOR][COLOR=#007700])&&([/COLOR][COLOR=#0000BB]c[/COLOR][COLOR=#007700]+[/COLOR][COLOR=#0000BB]a[/COLOR][COLOR=#007700]>=[/COLOR][COLOR=#0000BB]b[/COLOR][COLOR=#007700]))
{
[/COLOR][COLOR=#0000BB]printf[/COLOR][COLOR=#007700]([/COLOR][COLOR=#DD0000]"%f, %f, %f thoa man la 3 canh cua tam giac!\n\n"[/COLOR][COLOR=#007700],[/COLOR][COLOR=#0000BB]a[/COLOR][COLOR=#007700],[/COLOR][COLOR=#0000BB]b[/COLOR][COLOR=#007700],[/COLOR][COLOR=#0000BB]c[/COLOR][COLOR=#007700]);
if (([/COLOR][COLOR=#0000BB]a[/COLOR][COLOR=#007700]==[/COLOR][COLOR=#0000BB]b[/COLOR][COLOR=#007700])&&(([/COLOR][COLOR=#0000BB]a[/COLOR][COLOR=#007700]!=[/COLOR][COLOR=#0000BB]c[/COLOR][COLOR=#007700])||([/COLOR][COLOR=#0000BB]b[/COLOR][COLOR=#007700]!=[/COLOR][COLOR=#0000BB]c[/COLOR][COLOR=#007700])))
[/COLOR][COLOR=#0000BB]printf[/COLOR][COLOR=#007700]([/COLOR][COLOR=#DD0000]"Tam giac Can tai C"[/COLOR][COLOR=#007700]);
else if (([/COLOR][COLOR=#0000BB]a[/COLOR][COLOR=#007700]==[/COLOR][COLOR=#0000BB]c[/COLOR][COLOR=#007700])&&(([/COLOR][COLOR=#0000BB]a[/COLOR][COLOR=#007700]!=[/COLOR][COLOR=#0000BB]b[/COLOR][COLOR=#007700])||([/COLOR][COLOR=#0000BB]c[/COLOR][COLOR=#007700]!=[/COLOR][COLOR=#0000BB]b[/COLOR][COLOR=#007700])))
[/COLOR][COLOR=#0000BB]printf[/COLOR][COLOR=#007700]([/COLOR][COLOR=#DD0000]"Tam giac Can tai B"[/COLOR][COLOR=#007700]);
else if (([/COLOR][COLOR=#0000BB]c[/COLOR][COLOR=#007700]==[/COLOR][COLOR=#0000BB]b[/COLOR][COLOR=#007700])&&(([/COLOR][COLOR=#0000BB]c[/COLOR][COLOR=#007700]!=[/COLOR][COLOR=#0000BB]a[/COLOR][COLOR=#007700])||([/COLOR][COLOR=#0000BB]b[/COLOR][COLOR=#007700]!=[/COLOR][COLOR=#0000BB]a[/COLOR][COLOR=#007700])))
[/COLOR][COLOR=#0000BB]printf[/COLOR][COLOR=#007700]([/COLOR][COLOR=#DD0000]"Tam giac Can tai A"[/COLOR][COLOR=#007700]);
else if(([/COLOR][COLOR=#0000BB]a[/COLOR][COLOR=#007700]==[/COLOR][COLOR=#0000BB]b[/COLOR][COLOR=#007700])&&([/COLOR][COLOR=#0000BB]b[/COLOR][COLOR=#007700]==[/COLOR][COLOR=#0000BB]c[/COLOR][COLOR=#007700]))
[/COLOR][COLOR=#0000BB]printf[/COLOR][COLOR=#007700]([/COLOR][COLOR=#DD0000]"Tam giac Deu!"[/COLOR][COLOR=#007700]);
else if([/COLOR][COLOR=#0000BB]a[/COLOR][COLOR=#007700]*[/COLOR][COLOR=#0000BB]a[/COLOR][COLOR=#007700]==[/COLOR][COLOR=#0000BB]b[/COLOR][COLOR=#007700]*[/COLOR][COLOR=#0000BB]b[/COLOR][COLOR=#007700]+[/COLOR][COLOR=#0000BB]c[/COLOR][COLOR=#007700]*[/COLOR][COLOR=#0000BB]c[/COLOR][COLOR=#007700])
[/COLOR][COLOR=#0000BB]printf[/COLOR][COLOR=#007700]([/COLOR][COLOR=#DD0000]"Tam giac Vuong tai A"[/COLOR][COLOR=#007700]);
else if([/COLOR][COLOR=#0000BB]b[/COLOR][COLOR=#007700]*[/COLOR][COLOR=#0000BB]b[/COLOR][COLOR=#007700]==[/COLOR][COLOR=#0000BB]a[/COLOR][COLOR=#007700]*[/COLOR][COLOR=#0000BB]a[/COLOR][COLOR=#007700]+[/COLOR][COLOR=#0000BB]c[/COLOR][COLOR=#007700]*[/COLOR][COLOR=#0000BB]c[/COLOR][COLOR=#007700])
[/COLOR][COLOR=#0000BB]printf[/COLOR][COLOR=#007700]([/COLOR][COLOR=#DD0000]"Tam giac Vuong tai B"[/COLOR][COLOR=#007700]);
else if([/COLOR][COLOR=#0000BB]c[/COLOR][COLOR=#007700]*[/COLOR][COLOR=#0000BB]c[/COLOR][COLOR=#007700]==[/COLOR][COLOR=#0000BB]b[/COLOR][COLOR=#007700]*[/COLOR][COLOR=#0000BB]b[/COLOR][COLOR=#007700]+[/COLOR][COLOR=#0000BB]a[/COLOR][COLOR=#007700]*[/COLOR][COLOR=#0000BB]a[/COLOR][COLOR=#007700])
[/COLOR][COLOR=#0000BB]printf[/COLOR][COLOR=#007700]([/COLOR][COLOR=#DD0000]"Tam giac Vuong tai C"[/COLOR][COLOR=#007700]);
else if (([/COLOR][COLOR=#0000BB]a[/COLOR][COLOR=#007700]+[/COLOR][COLOR=#0000BB]b[/COLOR][COLOR=#007700]==[/COLOR][COLOR=#0000BB]c[/COLOR][COLOR=#007700])||([/COLOR][COLOR=#0000BB]c[/COLOR][COLOR=#007700]+[/COLOR][COLOR=#0000BB]b[/COLOR][COLOR=#007700]==[/COLOR][COLOR=#0000BB]a[/COLOR][COLOR=#007700])||([/COLOR][COLOR=#0000BB]c[/COLOR][COLOR=#007700]+[/COLOR][COLOR=#0000BB]a[/COLOR][COLOR=#007700]==[/COLOR][COLOR=#0000BB]b[/COLOR][COLOR=#007700]))
[/COLOR][COLOR=#0000BB]printf[/COLOR][COLOR=#007700]([/COLOR][COLOR=#DD0000]"Tam giac bi Suy bien!"[/COLOR][COLOR=#007700]);
else
[/COLOR][COLOR=#0000BB]printf[/COLOR][COLOR=#007700]([/COLOR][COLOR=#DD0000]"Tam giac Thuong!"[/COLOR][COLOR=#007700]);
}
else
[/COLOR][COLOR=#0000BB]printf[/COLOR][COLOR=#007700]([/COLOR][COLOR=#DD0000]"%f, %f, %f khong thoa man la 3 canh cua tam giac!\n"[/COLOR][COLOR=#007700],[/COLOR][COLOR=#0000BB]a[/COLOR][COLOR=#007700],[/COLOR][COLOR=#0000BB]b[/COLOR][COLOR=#007700],[/COLOR][COLOR=#0000BB]c[/COLOR][COLOR=#007700]);
[/COLOR][COLOR=#0000BB]getch[/COLOR][COLOR=#007700]();
return [/COLOR][COLOR=#0000BB]0[/COLOR][COLOR=#007700];
}
3. Dùng mảng
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