世界上最早的算法：辗转相除法（求两个自然数最大公约数）
public class Euclideanalgorithm{ public static int getGCD(int a, int b) { if(a < 0 || b < 0) return -1; if(a < b) { int c = b; b = a; a = c; } int c = a % b; if(c == 0) return b; else return getGCD(b, c); } public static void main(String[] args) { System.out.println(getGCD(1254, 390)); }}

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