Algorithms & Properties

Possible sum of K distinct integers between 1 and N

let the sum be S,
we can form all numbers till $\dfrac{N(N+1)}{2}$
but if we are to use fixed K digits, the Range will be limited to $(K)(N)+(K-1)$

Sliding Window

• Use deque or vector when you also need to access every element while sliding
• Sliding Window for Maximum sum of K continous elements of vector vec

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vector<int> vec(n);
// Take Input
queue<int> sm;
int sum=0;
for (int i=0; i<n; i++){
    if (sm.size()>k){
        sum-=sm.front();
        sm.pop();
    }
    sm.push(vec[i]);
    sum+=vec[i];
    ans=max(sum,ans);
}

Photo by Pawel Czerwinski on Unsplash