<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 {
    unordered_map<int,int>idx,ridx;
    int solve(vector<int>&arr1,vector<int>&arr2,vector<vector<int>>&dp,int i,int last,int j){
        if(i==arr1.size()) return 0;
        int &ans=dp[i][last];
        if(ans!=-1) return ans;
        ans=1e9;
        while(j<arr2.size() and arr2[j]<=ridx[last]) j++;
        if(arr1[i]>ridx[last]) ans=min(ans,solve(arr1,arr2,dp,i+1,idx[arr1[i]],j));
        if(j<arr2.size()) ans=min(ans,1+solve(arr1,arr2,dp,i+1,idx[arr2[j]],j));
        return ans;
    }
public:
    int makeArrayIncreasing(vector<int>& arr1, vector<int>& arr2) {
        set<int>st;
        st.insert(-1);
        for(auto t:arr1) st.insert(t);
        for(auto t:arr2) st.insert(t);
        idx.clear(),ridx.clear();
        sort(arr2.begin(),arr2.end());
        int i=0;
        for(auto t:st) idx[t]=i,ridx[i]=t,i++;
        vector<vector<int>>dp(arr1.size(),vector<int>(idx.size(),-1));
        return solve(arr1,arr2,dp,0,0,0)==1e9?-1:solve(arr1,arr2,dp,0,0,0);
    }
};
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