约瑟夫环（约瑟夫问题）是一个数学的应用问题：已知n个人（以编号1，2，3...n分别表示）围坐在一张圆桌周围。从编号为k的人开始报数，数到m的那个人出列；他的下一个人又从1开始报数，数到m的那个人又出列；依此规律重复下去，直到圆桌周围的人全部出列。通常解决这类问题时我们把编号从0~n-1，最后[1]　结果+1即为原问题的解。(The Joseph ring (Joseph problem) is a mathematical application problem: known n individuals (with numbered 1, 2, 3... N respectively) sit around a round table. K from a number of people start off, the man out of the line to the m; his next person and from 1 to start off, count to m that another person out; so law be repeated until all of the people out around the table. When we usually solve this kind of problem, we have the number from 0~n-1, and the final [1] result +1 is the solution of the original problem.)