打印日历

题意:

　　输入年份和月份,打印出此年此月的日历.

思路:

　　利用蔡乐公式,计算出Y年M月1号是星期几,然后直接打印输出就好.

代码:

　　

#include <iostream>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <algorithm>
#include <queue>
#include <stack>
#include <vector>
using namespace std;
typedef long long LL;

int main(){
    //freopen("input.txt", "r", stdin);
    int YY, MM;
    int kas = 1;
    while(~scanf("%d%d", &YY, &MM)){
        int Y = YY, M = MM;
        int C, D = 1;
        C = Y / 100, Y %= 100;
        if(M < 3) M += 12, Y -= 1;
        int W = (Y + Y / 4 + C / 4 - 2 * C + 26 * (M + 1) / 10 + D - 1) % 7;
        while(W < 0) W += 7;
        // printf("%d\n", W);
        printf("Case %d:\n", kas++);
        printf("  Sun  Mon  Tue  Wed  Thu  Fri  Sat\n");
        int day = 1;
        int mday = -1;
        if(MM == 2){
            if( (YY % 4 == 0 && YY % 100 != 0 )|| ( YY % 400 == 0) ) mday = 29;
            else mday = 28;
        }
        else{
            if(MM == 1 || MM == 3 || MM == 5 || MM == 7 || MM == 8 || MM == 10 || MM == 12)mday = 31;
            else mday = 30;
        }
        for(int i = 0; i < 6; i++){
            int flag = 0;
            for(int j = 0; j < 7; j++){
                if(W != 0){
                    printf("     ");
                    W--;
                }
                else{
                    printf("%5d", day++);
                    if(day == mday + 1){
                        flag = 1;
                        break;
                    }
                }    
            }
            printf("\n");
            if(flag) break;
        }
    }
    return 0;
}