面试题43，44，45

三个抽象建模问题：

• 选择合理数据结构
• 分析模型中内在规律

面试题43：n个骰子点数

面试题44：扑克牌的顺子

 http://www.nowcoder.com/practice/762836f4d43d43ca9deb273b3de8e1f4?tpId=13&tqId=11198&rp=3&ru=/ta/coding-interviews&qru=/ta/coding-interviews/question-ranking

class Solution {
public:
    bool IsContinuous( vector<int> numbers ) {
        int len = numbers.size();
        sort(numbers.begin(),numbers.end());
        if(len <= 0)
            return false;
        int zero_count = 0;
        int gap_count = 0;
        for(int i = 0; i < len; i++)
        {
            if(numbers[i] == 0)
                zero_count++;
            else if( i + 1 < len)
            {
                if(numbers[i] == numbers[i+1])
                    return false;
                else
                    gap_count += numbers[i+1] - numbers[i] - 1;
            }
        }
        if(gap_count > zero_count)
            return false;
        else
            return true;
    }
};

 

面试题45：圆圈中最后剩下的数字

用list当作环形链表，当iterator遍历到end，设为begin

注意迭代器不能用四则运算，只能用自增自减，故在第22行用++，然后在26行要还原

int LastRemaining_Solution1(unsigned int n, unsigned int m)
{
    if(n < 1 || m < 1)
        return -1;

    unsigned int i = 0;

    list<int> numbers;
    for(i = 0; i < n; ++ i)
        numbers.push_back(i);

    list<int>::iterator current = numbers.begin();
    while(numbers.size() > 1)
    {
        for(int i = 1; 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);
}