第一题，根据公式可以推导出x=(a/b)*y, 那么x*y就完全取决于y，可以推导y的范围是[1,B]以及[b/a, (b/a)*A]，求出y满足这两个范围，且使得x为整数的(x,y)就可以了 package AliBaBa; import java.util.Scanner; public class probleam1 { public static void main(String[] args) { Scanner sc = new Scanner(System.in); while(sc.hasNext()){ long A = sc.nextLong(); long B = sc.nextLong(); long a = sc.nextLong(); long b = sc.nextLong(); //临时变量 先取到最大的那一个 long tem = Math.min(B, (b*A)/a); //往小了缩，直到x为整数 while(tem >= Math.ceil((double)b/a) && tem >= 1 && (a*tem)%b != 0){ tem--; } //不存在，到底了也没有能够满足的 if((a*tem)%b != 0){ System.out.println(0 + " " + 0); }else{ long y = tem; long x = (a*y)/b; System.out.println(x + " " + y); } } } }