<p>You are given two <strong>sorted</strong> arrays of distinct integers <code>nums1</code> and <code>nums2</code>.</p>

<p>A <strong>valid<strong><em> </em></strong>path</strong> is defined as follows:</p>

<ul>
	<li>Choose array <code>nums1</code> or <code>nums2</code> to traverse (from index-0).</li>
	<li>Traverse the current array from left to right.</li>
	<li>If you are reading any value that is present in <code>nums1</code> and <code>nums2</code> you are allowed to change your path to the other array. (Only one repeated value is considered in the valid path).</li>
</ul>

<p>The <strong>score</strong> is defined as the sum of unique values in a valid path.</p>

<p>Return <em>the maximum score you can obtain of all possible <strong>valid paths</strong></em>. Since the answer may be too large, return it modulo <code>10<sup>9</sup> + 7</code>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2020/07/16/sample_1_1893.png" style="width: 500px; height: 151px;" />
<pre>
<strong>Input:</strong> nums1 = [2,4,5,8,10], nums2 = [4,6,8,9]
<strong>Output:</strong> 30
<strong>Explanation:</strong> Valid paths:
[2,4,5,8,10], [2,4,5,8,9], [2,4,6,8,9], [2,4,6,8,10],  (starting from nums1)
[4,6,8,9], [4,5,8,10], [4,5,8,9], [4,6,8,10]    (starting from nums2)
The maximum is obtained with the path in green <strong>[2,4,6,8,10]</strong>.
</pre>

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

<pre>
<strong>Input:</strong> nums1 = [1,3,5,7,9], nums2 = [3,5,100]
<strong>Output:</strong> 109
<strong>Explanation:</strong> Maximum sum is obtained with the path <strong>[1,3,5,100]</strong>.
</pre>

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

<pre>
<strong>Input:</strong> nums1 = [1,2,3,4,5], nums2 = [6,7,8,9,10]
<strong>Output:</strong> 40
<strong>Explanation:</strong> There are no common elements between nums1 and nums2.
Maximum sum is obtained with the path [6,7,8,9,10].
</pre>

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

<ul>
	<li><code>1 &lt;= nums1.length, nums2.length &lt;= 10<sup>5</sup></code></li>
	<li><code>1 &lt;= nums1[i], nums2[i] &lt;= 10<sup>7</sup></code></li>
	<li><code>nums1</code> and <code>nums2</code> are strictly increasing.</li>
</ul>

class Solution {
public:
    long long m = 1e9+7;
    int maxSum(vector<int>& nums1, vector<int>& nums2) {
        int n1 = nums1.size(); int n2 = nums2.size();
        long long presum1[n1]; long long presum2[n2];
        presum1[0] = nums1[0]; presum2[0] = nums2[0];
        unordered_map<int,int>pos1,pos2;
        pos1[nums1[0]] = 1; pos2[nums2[0]] = 1;
        for(int i=1;i<n1;i++) {
            presum1[i] = nums1[i] + presum1[i-1];
            pos1[nums1[i]] = i+1;
        }
        for(int i=1;i<n2;i++) {
            presum2[i] = nums2[i] + presum2[i-1];
            pos2[nums2[i]] = i+1;
        }
        // for(auto i:presum1) cout << i << " ";
        // cout << endl;
        // for(auto i:presum2) cout << i << " ";
        // cout << endl;
        long long ans = 0;
        int prev1 = -1,prev2 = -1;
        for(int i=0;i<n1;i++) {
            if(pos2[nums1[i]]) {
                // cout << i << "->" << pos2[nums1[i]] << endl;
                if(prev1 == -1 and prev2 == -1) {
                    // cout << "--->" << max(presum1[i],presum2[pos2[nums1[i]]-1]) << endl;
                    ans = (max(presum1[i],presum2[pos2[nums1[i]]-1]) + ans);
                }
                else{
                    // cout << "=>" << max(presum1[i]-presum1[prev1],presum2[pos2[nums1[i]]-1]-presum2[prev2]) << endl;
                    ans = (max(presum1[i]-presum1[prev1],presum2[pos2[nums1[i]]-1]-presum2[prev2]) + ans) ;
                }
                prev1 = i; prev2 = pos2[nums1[i]]-1;
            }
        }
        // cout << presum1[n1-1] << " : " << presum2[n2-1] << " : " << ans << endl;
        if(prev1 != -1 and prev2 != -1)
        ans = (max(presum1[n1-1]-presum1[prev1],presum2[n2-1]-presum2[prev2]) + ans);
        else 
        ans = (max(presum1[n1-1],presum2[n2-1]) + ans);
        return ans%m;
    }
};
109330