Algorithm: Max Counters

Question

I have the following problem:

You are given N counters, initially set to 0, and you have two possible operations on them:

• increase(X) − counter X is increa

Answer 1

C++11 code:

#include 

vector solution(int N, vector &A) {

    vector hist(N, 0);

    int last_update = 0;
    int max_value = 0;

    for (auto i : A){

        if (1 <= i && i <= N){
            int& val = hist[i - 1];

            if (val < last_update)
                val = last_update + 1;
            else
                val++;

            if (max_value < val)
                max_value = val;
        }

        if (i == (N+1)){
            last_update = max_value;
        }

    }

    replace_if(hist.begin(), hist.end(), [last_update](int x){return x < last_update;}, last_update);

    return hist;
}