leetcode1713 得到子序列的最少操作次数

思路：

重新编号之后转化为LIS。

实现：

class Solution
{
public:
    int LIS(vector<int>& nums)
    {
        int n = nums.size();
        vector<int> v(1, -1);
        for (int i = 0; i < n; i++)
        {
            int p = lower_bound(v.begin(), v.end(), nums[i]) - v.begin() - 1;
            if (p + 1 == v.size()) v.push_back(nums[i]);
            else v[p + 1] = min(v[p + 1], nums[i]);
        }
        return v.size() - 1;
    }
    int minOperations(vector<int>& target, vector<int>& arr)
    {
        int n = target.size(), m = arr.size();
        unordered_map<int, int> mp;
        for (int i = 0; i < n; i++)
        {
            mp[target[i]] = i;
        }
        vector<int> v;
        for (int i = 0; i < m; i++)
        {
            if (!mp.count(arr[i])) continue;
            v.push_back(mp[arr[i]]);
        }
        return n - LIS(v);
    }
};