780. Reaching Points.c

/*
780. Reaching Points

A move consists of taking a point (x, y) and transforming it to either (x, x+y) or (x+y, y).

Given a starting point (sx, sy) and a target point (tx, ty), return True if and only if a sequence of moves exists to transform the point (sx, sy) to (tx, ty). Otherwise, return False.

Examples:
Input: sx = 1, sy = 1, tx = 3, ty = 5
Output: True
Explanation:
One series of moves that transforms the starting point to the target is:
(1, 1) -> (1, 2)
(1, 2) -> (3, 2)
(3, 2) -> (3, 5)

Input: sx = 1, sy = 1, tx = 2, ty = 2
Output: False

Input: sx = 1, sy = 1, tx = 1, ty = 1
Output: True



Note:


	sx, sy, tx, ty will all be integers in the range [1, 10^9].
*/


bool reachingPoints(int sx, int sy, int tx, int ty){
#if 0
    if (sx == tx && sy == ty) return true;
    if (sx > tx || sy > ty) return false;
    return (reachingPoints(sx, sx + sy, tx, ty) ||
            reachingPoints(sx + sy, sy, tx, ty));
#else
    while (tx >= sx && ty >= sy) {
        if (tx == sx && ty == sy) return true;
        if (tx > ty) {
            tx -= ty;
        } else {
            ty -= tx;
        }
    }
    return false;
#endif
}


/*
Difficulty:Hard


*/