<p>Given an integer array <code>nums</code> and two integers <code>lower</code> and <code>upper</code>, return <em>the number of range sums that lie in</em> <code>[lower, upper]</code> <em>inclusive</em>.</p>

<p>Range sum <code>S(i, j)</code> is defined as the sum of the elements in <code>nums</code> between indices <code>i</code> and <code>j</code> inclusive, where <code>i &lt;= j</code>.</p>

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

<pre>
<strong>Input:</strong> nums = [-2,5,-1], lower = -2, upper = 2
<strong>Output:</strong> 3
<strong>Explanation:</strong> The three ranges are: [0,0], [2,2], and [0,2] and their respective sums are: -2, -1, 2.
</pre>

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

<pre>
<strong>Input:</strong> nums = [0], lower = 0, upper = 0
<strong>Output:</strong> 1
</pre>

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

<ul>
	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
	<li><code>-2<sup>31</sup> &lt;= nums[i] &lt;= 2<sup>31</sup> - 1</code></li>
	<li><code>-10<sup>5</sup> &lt;= lower &lt;= upper &lt;= 10<sup>5</sup></code></li>
	<li>The answer is <strong>guaranteed</strong> to fit in a <strong>32-bit</strong> integer.</li>
</ul>

class Solution {
public:
    int solve(int s, int e, vector<int>& nums, int lower, int upper){
        if(s == e) {
            if(nums[s]>=lower && nums[s]<=upper) return 1;
            else return 0;
        }

        int mid = (s+e)/2;
        int l = solve(s, mid, nums, lower, upper);
        int r = solve(mid+1, e, nums, lower, upper);

        int ans = l+r;

        vector<long long> left, right;
        long long sum = 0;
        for(int i=mid; i>=s; i--){
            sum += (long long)nums[i];
            left.push_back(sum);
        }
        sum = 0;
        for(int i=mid+1; i<=e; i++){
            sum += (long long)nums[i];
            right.push_back(sum);
        }
        sort(left.begin(), left.end());
        sort(right.begin(), right.end());
        int mer = 0;
        for(int i=0; i<left.size(); i++){
            long long u1 = (long long)lower-left[i];
            long long u2 = (long long)upper-left[i];
            auto a = lower_bound(right.begin(),right.end(),u1);
            auto b = upper_bound(right.begin(),right.end(),u2);
            int l1 = right.end()-a;
            int l2 = right.end()-b;
            mer+=abs(l1-l2);
        }

        return ans+mer;
    }
    int countRangeSum(vector<int>& nums, int lower, int upper) {
        return solve(0, nums.size()-1, nums, lower, upper);
    }
};
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