<p>Given two integer arrays&nbsp;<code>arr1</code> and <code>arr2</code>, return the minimum number of operations (possibly zero) needed&nbsp;to make <code>arr1</code> strictly increasing.</p>

<p>In one operation, you can choose two indices&nbsp;<code>0 &lt;=&nbsp;i &lt; arr1.length</code>&nbsp;and&nbsp;<code>0 &lt;= j &lt; arr2.length</code>&nbsp;and do the assignment&nbsp;<code>arr1[i] = arr2[j]</code>.</p>

<p>If there is no way to make&nbsp;<code>arr1</code>&nbsp;strictly increasing,&nbsp;return&nbsp;<code>-1</code>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> arr1 = [1,5,3,6,7], arr2 = [1,3,2,4]
<strong>Output:</strong> 1
<strong>Explanation:</strong> Replace <code>5</code> with <code>2</code>, then <code>arr1 = [1, 2, 3, 6, 7]</code>.
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> arr1 = [1,5,3,6,7], arr2 = [4,3,1]
<strong>Output:</strong> 2
<strong>Explanation:</strong> Replace <code>5</code> with <code>3</code> and then replace <code>3</code> with <code>4</code>. <code>arr1 = [1, 3, 4, 6, 7]</code>.
</pre>

<p><strong class="example">Example 3:</strong></p>

<pre>
<strong>Input:</strong> arr1 = [1,5,3,6,7], arr2 = [1,6,3,3]
<strong>Output:</strong> -1
<strong>Explanation:</strong> You can&#39;t make <code>arr1</code> strictly increasing.</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= arr1.length, arr2.length &lt;= 2000</code></li>
	<li><code>0 &lt;= arr1[i], arr2[i] &lt;= 10^9</code></li>
</ul>

<p>&nbsp;</p>

class Solution {
public:
    int f(const set<int>& bankList,vector<int>& nList,int idx){
        if(idx == nList.size())
            return 0;
        const int prev = nList[idx-1];
        if(mm[idx].count(prev)){
            return mm[idx][prev];
        }
        int& cur = nList[idx];
        auto it = bankList.upper_bound(prev);
        int ret = -1;
        if(it == bankList.end()){
            if(cur <= prev){
                return -1;
            }
            else{
                ret = f(bankList,nList,idx+1);
            }
        }
        else{
            if(cur > prev){
                if(*it < cur){
                    int bak = cur;

                    cur = *it;
                    int op1 =  f(bankList,nList,idx+1);
                    if(op1 != -1){
                        op1++;
                    }
                    cur = bak;

                    int op2 = f(bankList,nList,idx+1);

                    if(op1 == -1 && op2 == -1){
                        return -1;
                    }
                    else if(op1 == -1){
                        ret = op2;
                    }
                    else if(op2 == -1){
                        ret = op1;
                    }
                    else
                        ret = min(op1,op2);
                }
                else{
                    ret = f(bankList,nList,idx+1);
                }
            }
            else{
                int bak = cur;
                cur = *it;
                int tmp =   f(bankList,nList,idx+1);
                if(tmp == -1){
                    ret = -1;
                }
                else{
                    ret = tmp+1;
                }
                cur = bak;
            }

        }

        mm[idx][prev] = ret;
        return ret;

    }
    vector<map<int,int>> mm;
    int makeArrayIncreasing(vector<int>& arr1, vector<int>& arr2) {
        set<int> bankList(arr2.begin(), arr2.end());
        arr1.insert(arr1.begin() , INT_MIN);
        mm.resize(arr1.size());
        return f(bankList,arr1,1);

    }
};
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