#88 A

problem link http://codeforces.com/contest/117/problem/A

19:18 - 20:42

3 key point of this problem.

　　a) determin which is the current floor.

　　b) determin elevator direction

　　c) judge the time base on the s, cf, f relationship and direction. ( s--start floor, cf--current floor, f--final floor )

None of the above point can be omitted.

#include <stdio.h>

int main() {
    int n, m;
    scanf("%d %d", &n, &m);
    int i, s, f, t, cf, d;
    int wait, go, time;
    for( i=0;i<n;i++ ) {
        scanf("%d %d %d", &s, &f, &t);
        if( s == f ) {
            printf("%d\n", t);
            continue;
        }
        d = (t/(m-1)) % 2;
        if( d == 0 )
            cf = (t % (m-1)) + 1;
        else 
            cf = m - (t % (m-1));

        if( cf < s && s < f ) {
            if( d == 0 ) // up
                time = f - cf;
            else // down
                time = cf - 1 + f - 1;
        }
        else if( s < cf && cf < f ) {
            if ( d == 0 ) // up
                time = m - cf + m - 1 + f - 1;
            else // down
                time = cf - 1 + f - 1;
        }
        else if( s < f && f < cf ) {
            if ( d == 0 ) // up
                time = m - cf + m - 1 + f - 1;
            else // down
                time = cf - 1 + f - 1;
        }
        else if( cf < f && f < s ) {
            if ( d == 0 ) // up
                time = m - cf + m - f;
            else // down
                time = cf - 1 + m - 1 + m - f;
        }
        else if( f < cf && cf < s ) {
            if ( d == 0 ) // up
                time = m - cf + m - f;
            else // down
                time = cf - 1 + m - 1 + m - f;
        }
        else if( f < s && s < cf ) { 
            if ( d == 0 ) // up
                time = m - cf + m - f;
            else // down
                time = cf - f;
        }
        else if( s == cf && cf < f ) {
            if( d == 0 ) // up
                time = f - cf;
            else // down
                time = cf - 1 + f - 1;
        }
        else if( s < cf && cf == f ) {
            if( d == 0 ) // up
                time = m - cf + m - 1 + f - 1;
            else // down
                time = cf - 1 + f - 1;
        }
        else if( f == cf && cf < s ) {
            if( d == 0 ) // up
                time = m - cf + m - f;
            else // down
                time = cf - 1 + m - 1 + m - f;
        }
        else if( f < cf && cf == s ) { 
            if( d == 0 ) // up
                time = m - cf + m - f;
            else // down
                time = cf - f;
        }

        printf("%d\n", time + t);
    }

    return 0;
}