如题所述
//第ä¸é¢
#include <stdio.h>
#include <stdlib.h>
int main()
{
int n;
printf( "请è¾å ¥é¡¹æ°:" );
scanf( "%d", &n );
if( n%2 !=0 )
{
printf( "sum=%d\n", (n/2)*(-2) + 2*n-1 ); //è§å¯æ¯ä¸¤é¡¹çå为-2ï¼å½é¡¹æ°ä¸ºå¥æ°æ¶å¤å ä¸é¡¹.
}
else
{
printf( "sum=%d\n", (n/2)*(-2) );
}
system("pause");
return 0;
}
//第äºé¢
#include <stdio.h>
#include <stdlib.h>
#define NUM 2 //æ°å
#define N 5 //项æ°
int main()
{
int i, j, sum = 0, tmp = 0;
for( i=1; i<=N; i++ )
{
tmp = tmp*10 + NUM; //è§å¾:a(n) = a(n-1)*10 + NUM
sum += tmp; //æ±å.
}
printf( "sum=%d\n", sum );
system("pause");
return 0;
}
//第ä¸é¢
#include <stdio.h>
#include <stdlib.h>
int main()
{
int i, j, k;
int total = 0;
for( i=3; i<=6; i++ )
{
for( j=3; j<=6; j++ )
{
for( k=3; k<=6; k++ )
{
if( i!=j && i!=k && j!=k ) //å¦æä¸ä¸ªæ°ä¸¤ä¸¤é½ä¸ç¸çï¼å°±è¾åº.
{
printf( "%d%d%d\t", i, j, k );
total++;
if( total%6 == 0 ) //æ¯è¡è¾åº6个.
{
printf( "\n" );
}
}
}
}
}
system("pause");
return 0;
}
//第åé¢
#include <stdio.h>
#include <stdlib.h>
#define NUM 4 //èªå®ä¹è±å½¢ç大å°
int main()
{
int i,j,k;
for( i=-NUM; i<=NUM; i++ )
{
k = i>0?i:-i; //å©ç¨å¾å½¢ç对称æ§.
for( j=k; j>0; j-- )
{
printf( " " );
}
for( j=2*(NUM-k+1)-1; j>0; j--) //æ¯è¡è¾åº*çè§å¾æ¯: 2*n-1
{
printf( "*" );
}
printf( "\n" );
}
system( "pause" );
return 0;
}
//第äºé¢
#include <stdio.h>
#include <stdlib.h>
enum s{ x, y, z };
int main()
{
int a, b, c;
for( a=x; a<=z; a++ )
{
for( b=x; b<=z; b++ )
{
for( c=x; c<=z; c++ )
{
if( a!=x && c!=x && c!=z && a!=b && a!=c && b!=c ) //ä¸ä¸ªäºä¸ç¸çï¼å ä¸å ¶å®ä¸ä¸ªæ¡ä»¶æ»¡è¶³
{
printf( "a:%c\nb:%c\nc:%c\n", 'x'+a, 'x'+b, 'x'+c );
}
}
}
}
system("pause");
return 0;
}
//ææ¶é´æ¶ï¼ä½ è¿æ¯èªå·±åä¸ï¼è¿æ ·æä¼æè¿æ¥ã
#include <stdio.h>
#include <stdlib.h>
int main()
{
int n;
printf( "请è¾å ¥é¡¹æ°:" );
scanf( "%d", &n );
if( n%2 !=0 )
{
printf( "sum=%d\n", (n/2)*(-2) + 2*n-1 ); //è§å¯æ¯ä¸¤é¡¹çå为-2ï¼å½é¡¹æ°ä¸ºå¥æ°æ¶å¤å ä¸é¡¹.
}
else
{
printf( "sum=%d\n", (n/2)*(-2) );
}
system("pause");
return 0;
}
//第äºé¢
#include <stdio.h>
#include <stdlib.h>
#define NUM 2 //æ°å
#define N 5 //项æ°
int main()
{
int i, j, sum = 0, tmp = 0;
for( i=1; i<=N; i++ )
{
tmp = tmp*10 + NUM; //è§å¾:a(n) = a(n-1)*10 + NUM
sum += tmp; //æ±å.
}
printf( "sum=%d\n", sum );
system("pause");
return 0;
}
//第ä¸é¢
#include <stdio.h>
#include <stdlib.h>
int main()
{
int i, j, k;
int total = 0;
for( i=3; i<=6; i++ )
{
for( j=3; j<=6; j++ )
{
for( k=3; k<=6; k++ )
{
if( i!=j && i!=k && j!=k ) //å¦æä¸ä¸ªæ°ä¸¤ä¸¤é½ä¸ç¸çï¼å°±è¾åº.
{
printf( "%d%d%d\t", i, j, k );
total++;
if( total%6 == 0 ) //æ¯è¡è¾åº6个.
{
printf( "\n" );
}
}
}
}
}
system("pause");
return 0;
}
//第åé¢
#include <stdio.h>
#include <stdlib.h>
#define NUM 4 //èªå®ä¹è±å½¢ç大å°
int main()
{
int i,j,k;
for( i=-NUM; i<=NUM; i++ )
{
k = i>0?i:-i; //å©ç¨å¾å½¢ç对称æ§.
for( j=k; j>0; j-- )
{
printf( " " );
}
for( j=2*(NUM-k+1)-1; j>0; j--) //æ¯è¡è¾åº*çè§å¾æ¯: 2*n-1
{
printf( "*" );
}
printf( "\n" );
}
system( "pause" );
return 0;
}
//第äºé¢
#include <stdio.h>
#include <stdlib.h>
enum s{ x, y, z };
int main()
{
int a, b, c;
for( a=x; a<=z; a++ )
{
for( b=x; b<=z; b++ )
{
for( c=x; c<=z; c++ )
{
if( a!=x && c!=x && c!=z && a!=b && a!=c && b!=c ) //ä¸ä¸ªäºä¸ç¸çï¼å ä¸å ¶å®ä¸ä¸ªæ¡ä»¶æ»¡è¶³
{
printf( "a:%c\nb:%c\nc:%c\n", 'x'+a, 'x'+b, 'x'+c );
}
}
}
}
system("pause");
return 0;
}
//ææ¶é´æ¶ï¼ä½ è¿æ¯èªå·±åä¸ï¼è¿æ ·æä¼æè¿æ¥ã
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