<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:
    long long int count(vector<int>& v,int k,int l,int r){
        if(l>r){
            return 0;
        }
        if(l==r){
            if(v[l]<=k){
                return 1;
            }
            return 0;
        }
        int mid=(l+r)/2;
        vector<long long int> temp;
        long long int prev=0;
        long long cnt=0;
        for(int i=mid+1;i<=r;i++){
            temp.push_back(v[i]+prev);
            prev+=v[i];
        }
        sort(temp.begin(),temp.end());
        prev=0;
        for(int i=mid;i>=l;i--){
            prev+=v[i];
            auto it=lower_bound(temp.begin(),temp.end(),k-prev+1);
            if(!temp.empty()){
                int dist=it-temp.begin();
                cnt+=dist;
            }
        }
        return cnt+count(v,k,l,mid)+count(v,k,mid+1,r);
    }
    int countRangeSum(vector<int>& nums, int lower, int upper) {
        int n=nums.size();
        long long int temp=count(nums,upper,0,n-1);
        temp-=count(nums,lower-1,0,n-1);
        int ans=temp;
        return ans;
    }
};
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