ZeroJudge [a263: 日期差幾天] by Go-Ice

/*
    Name: ZeroJudge a263: 日期差幾天
    Author: LinChuWen
    Date: 17/04/15
    Description: a program that counts days between two dates
*/

#include <stdio.h>
#include <stdlib.h>

int monthLength();
int testLeapYear();
void arrangeOrder();
void switchDate();

int main(){
    int y1, m1, d1;
    int y2, m2, d2;
    int dayAmount;
    int cnt;

    while ( scanf("%d %d %d %d %d %d", &y1, &m1, &d1, &y2, &m2, &d2)!=EOF ){
        /* reset variable */
        dayAmount = 0;

        arrangeOrder( &y1, &m1, &d1, &y2, &m2, &d2 );

        /* count days between Date1 and Date2 */
        if ( y1 > y2 ){
            /* count days between y1 and y2 */
            for ( cnt=y2+1 ; cnt<y1 ; cnt++ )
                dayAmount += 365;

            /* count leap years between y1 and y2 */
            for ( cnt=y2-y2%4+4 ; cnt<y1 ; cnt+=4 )
                if ( testLeapYear(cnt) == 1 )
                    dayAmount++;

            /*  count days from the beginning of the year to Date1 */
            dayAmount += d1;
            for ( cnt=1 ; cnt<m1 ; cnt++ )
                dayAmount += monthLength( y1, cnt );

            /* count days from Date2 to the end of the year */
            dayAmount += monthLength( y2, m2 ) - d2;
            for ( cnt=m2+1 ; cnt<=12 ; cnt++ )
                dayAmount += monthLength( y2, cnt );

        } /* END if (y1>y2) */

        else if ( y1 == y2 ){
            if ( m1 > m2 ){
                /* count days between m1 and m2 */
                for ( cnt=m2+1 ; cnt<m1 ; cnt++ )
                    dayAmount += monthLength( y1, cnt );
                dayAmount += monthLength( y2, m2 ) - d2;
                dayAmount += d1;
            } /* END if (m1>m2) */

            else if ( m1 == m2 ){
                if ( d1 > d2 )
                    dayAmount = d1 - d2;

                else if ( d1 == d2 )
                    dayAmount = 0;
            } /* END else if (m1=m2) */
        } /* END else if (y1=y2) */

        /* print out the answer, dayAmount */
        printf("%d\n", dayAmount);

    } /* END outer while */

    system("PAUSE");
    return 0;
} /* END main()*/

int testLeapYear( int year ){
    /* return 1 represented "true" (leap year) */
    /* return 0 represented "false" (common year) */
    if ( year%4 == 0 ){
        if ( year%100 == 0 ){
            if ( year%400 == 0 )
                return 1;
            else
                return 0;
        }
        else
            return 1;
    }
    else
        return 0;
} /* END testLeapYear() */

int monthLength( int year, int month ){
    int monthDays[12] = {31, 0, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

    if ( month == 2 ){
        if ( testLeapYear(year) == 1 )
            return 29;
        else
            return 28;
    }
    else
        return monthDays[--month];

} /* END monthLength() */

void switchDate( int *y1, int *m1, int *d1, int *y2, int *m2, int *d2 ){
    int reg;
    reg = *y1;  *y1 = *y2;  *y2 = reg;
    reg = *m1;  *m1 = *m2;  *m2 = reg;
    reg = *d1;  *d1 = *d2;  *d2 = reg;
} /* END switchDate() */

void arrangeOrder( int *y1, int *m1, int *d1, int *y2, int *m2, int *d2 ){
    if ( *y1 < *y2 )
        switchDate( y1, m1, d1, y2, m2, d2 );

    else if ( *y1 == *y2 )
        if ( *m1 < *m2 )
            switchDate( y1, m1, d1, y2, m2, d2 );

        else if ( *m1 == *m2 )
            if ( *d1 < *d2 )
                switchDate( y1, m1, d1, y2, m2, d2 );

} /* END arrangeOrder() */