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Java-based LeetCode algorithm problem solutions, regularly updated

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package g0701_0800.s0780_reaching_points;

// #Hard #Math #2022_03_26_Time_0_ms_(100.00%)_Space_41.3_MB_(32.70%)

/**
 * 780 - Reaching Points\.
 *
 * Hard
 *
 * Given four integers `sx`, `sy`, `tx`, and `ty`, return `true` _if it is possible to convert the point_ `(sx, sy)` _to the point_ `(tx, ty)` _through some operations__, or_ `false` _otherwise_.
 *
 * The allowed operation on some point `(x, y)` is to convert it to either `(x, x + y)` or `(x + y, y)`.
 *
 * **Example 1:**
 *
 * **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) 
 *
 * **Example 2:**
 *
 * **Input:** sx = 1, sy = 1, tx = 2, ty = 2
 *
 * **Output:** false 
 *
 * **Example 3:**
 *
 * **Input:** sx = 1, sy = 1, tx = 1, ty = 1
 *
 * **Output:** true 
 *
 * **Constraints:**
 *
 * *   1 <= sx, sy, tx, ty <= 10⁹
**/
public class Solution {
    public boolean reachingPoints(int sx, int sy, int tx, int ty) {
        while (tx >= sx && ty >= sy) {
            if (tx > ty) {
                if (ty == sy) {
                    // ty==sy
                    return (tx - sx) % sy == 0;
                } else {
                    // ty > sy
                    tx %= ty;
                }
            } else if (sx == tx) {
                // ty >= tx
                return (ty - sy) % sx == 0;
            } else {
                // (tx > sx)
                ty %= tx;
            }
        }
        return false;
    }
}