剑指Offer45 约瑟夫环

 /*************************************************************************
     > File Name: 45_LastNumberInCircle.cpp
     > Author: Juntaran
     > Mail: JuntaranMail@gmail.com
     > Created Time: 2016年09月04日 星期日 20时21分57秒
  ************************************************************************/

 #include <stdio.h>
 #include <bits/stdc++.h>

 using namespace std;

 // 环形链表
 int LastRemaining1(int n, int m)
 {
     if (n< || m<)
         return -;

     int i = ;

     list<int> numbers;
     for (int i = ; i < n; ++i)
         numbers.push_back(i);

     list<int>::iterator current = numbers.begin();
     while (numbers.size() > )
     {
         for (int i = ; i < m; ++i)
         {
             current ++;
             if (current == numbers.end())
                 current = numbers.begin();
         }
         list<int>::iterator next = ++current;
         if (next == numbers.end())
             next = numbers.begin();

         --current;
         numbers.erase(current);
         current = next;
     }
     return *current;
 }

 // 数组模拟环
 int LastRemaining2(int n, int m)
 {
     if (n< || m<)
         return -;

     int array[n];
     int i = -;
     int step = ;
     int count = n;

     while (count > )
     {
         i ++;
         if (i >= n)            // 模拟环
             i = ;
         if (array[i] == -)
             continue;
         step ++;
         if (step == m)
         {
             array[i] = -;
             step = ;
             count --;
         }
     }
     int ret = i;
     return ret;
 }

 // 数学解法
 int LastRemaining3(int n, int m)
 {
     if (n< || m<)
         return -;

     int ret = ;
     for (int i = ; i <= n; ++i)
         ret = (ret + m) % i;

     return ret;
 }

 int main()
 {
     int n = ;
     int m = ;

     int ret1 = LastRemaining1(n, m);
     int ret2 = LastRemaining2(n, m);
     int ret3 = LastRemaining3(n, m);

     printf("ret1 is %d\n", ret1);
     printf("ret2 is %d\n", ret2);
     printf("ret3 is %d\n", ret3);

     return ;
 }