C :

#include<stdio.h>
int main()
{
	int n,m;
	while(scanf("%d %d",&n,&m)!=EOF)
	{
		int i,j,k=1,s=1,a[6][7];
		for(i=0;i<6;i++)
			for(j=0;j<7;j++)
				a[i][j]=0;
		int tab[13]={0,31,28,31,30,31,30,31,31,30,31,30,31};
		int t=tab[m];
		if((n%4==0&&n%100!=0||n%400==0)&&m==2)
			t=t+1;
		if(m==1||m==2)
		{
			m=m+12;
			n=n-1;
		}
		int w;
		w=(1+2*m+3*(m+1)/5+n+n/4-n/100+n/400+1)%7;	
		printf("Su Mo Tu We Th Fr Sa\n");
		for(i=w;i<7;i++)
			a[0][i]=k++;
		if(a[0][0]==1)
		{
			printf(" 1");
			s++;
		}
		else
			printf("  ");
		for(i=1;i<7;i++)
		{
			if(a[0][i]!=0)
			{
				s++;
				printf(" %2d",a[0][i]);
			}
			else
				printf("   ");
		}
		printf("\n");
		int ok=0;
		for(i=1;i<6;i++)
		{
			for(j=0;j<7;j++)
			{
				a[i][j]=k++;
				if(k>t)
				{
					ok=1;
					break;
				}
			}
			if(ok)
				break;
		}
		ok=0;
		for(i=1;i<6;i++)
		{
			printf("%2d",a[i][0]);
			s++;
			if(k==s)
			{
				printf("\n");
				break;
			}
			for(j=1;j<7;j++)
			{
				printf(" %2d",a[i][j]);
				s++;
				if(k==s)
				{
					ok=1;
					break;
					
				}	
			}
			printf("\n");
			if(ok)
				break;
		}
	}
	return 0;
}

C++ :

#include <cstdio>
#include <cstring>
#include <cmath>
#include <iostream>
using namespace std;
 
int day[13]= { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 };
 
int mday[13]= { 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }; 
 
int firstday[2055]; 
 
bool is_spe( int year )
{
    if( ( year% 4== 0&& year% 100!= 0 )|| year% 400== 0 )
    {
        return true;
    }
    else
    {
        return false;
    }
}
 
int main(  )
{
    firstday[2011]= 6;
    for( int i= 2010; i>= 1; --i )
    {
        int curday= is_spe( i )? 366: 365;
        curday%= 7;
        firstday[i]= firstday[i+ 1]- curday;
        if( firstday[i]<= 0 )  firstday[i]+= 7;
    }
    for( int i= 2012; i<= 2050; ++i )
    {
        int curday= is_spe( i- 1 )? 366: 365;
        curday%= 7;
        firstday[i]= firstday[i- 1]+ curday;
        firstday[i]%= 7;
        if( !firstday[i] )  firstday[i]= 7;
    }
    int year, mon;
    while( scanf( "%d %d", &year, &mon )!= EOF )
    {
        int fday= firstday[year], num_day, sign;
        if( is_spe( year )&& mon> 2 )
        {
            num_day= day[mon- 1];
        }
        else
        {
            num_day= day[mon- 1]- 1;
        }
        sign= ( fday+ num_day )% 7;
        if( !sign )  sign= 7;
        int num_mday= ( is_spe( year )&& mon== 2 )? 29: mday[mon];
        puts( "Su Mo Tu We Th Fr Sa" );
        for( int i= 1; i<= num_mday; ++i )
        {
            int temp= ( sign+ i )% 7;
            for( int j= 0; i== 1&& j< temp; ++j )
            {
                printf( j== 0? "  ": "   " );
            }
            if( temp== 0 )
            {
                printf( "%2d", i );
            }
            else if( temp== 6 )
            {
                printf( "%3d\n", i );
            }
            else
            {
                printf( "%3d", i );
            }
            if( i== num_mday&& temp!= 6 )
            {
                puts( "" );
            }
        }
    }
    return 0;
}