leetcode-1054. 距离相等的条形码

题目描述

基本思路
1、从下标0位开始放置数字，直到结尾
2、从剩余数字中选择出现次数最多的数字m和次多的数字n，依次放置到结果列表
3、重复步骤2直到放置完毕

static bool cmp(std::pair<int,int> &p1, std::pair<int,int> &p2)
{
	return p1.second < p2.second;
}

vector<int> rearrangeBarcodes(vector<int>& barcodes) 
{
    unordered_map<int, int> m;			//[num, count]
	
	// 统计每个数字的出现次数
    for (auto iter = barcodes.begin(); iter != barcodes.end(); iter++)
    {
        m[*iter]++;
    }

    vector<pair<int, int>> vec;
    for (auto iter = m.begin(); iter != m.end(); iter++)
    {
        vec.push_back(make_pair((*iter).first, (*iter).second));
    }

	// 按照出现次数构建最大堆
    make_heap(vec.begin(), vec.end(), cmp);
    vector<int> res(barcodes.size());

    pair<int, int> st = make_pair(0, 0);
    pair<int, int> nd = make_pair(0, 0);

    int i = 0;
    while (i < res.size())
    {
        if (!vec.empty())
        {
            st = vec[0];
            pop_heap(vec.begin(), vec.end(), cmp);
            vec.pop_back();
        }

        if (!vec.empty())
        {
            nd = vec[0];
            pop_heap(vec.begin(), vec.end(), cmp);
            vec.pop_back();
        }

        if (st.second > 0)
        {
            res[i] = st.first;
            st.second--;
            i++;
        }

        if (st.second > 0)
        {
            vec.push_back(st);
            push_heap(vec.begin(), vec.end(), cmp);
        }

        if (nd.second > 0)
        {
            res[i] = nd.first;
            nd.second--;
            i++;
        }

        if (nd.second > 0)
        {
            vec.push_back(nd);
            push_heap(vec.begin(), vec.end(), cmp);
        }
    }

    return res;
}