MissingInteger

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problem

solution

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// you can use includes, for example:
// #include <algorithm>

// you can write to stdout for debugging purposes, e.g.
// cout << "this is a debug message" << endl;
#include <algorithm>
int solution(vector<int> &A) {
    // write your code in C++14 (g++ 6.2.0)
    sort(A.begin(), A.end());
    int n = A.size(), c =1;
    for(int i=0;i<n;++i){
        if(A[i] == c) c++;
        while(i<n-1 && A[i] == A[i+1] ) i++;
    }
    return c;
}

analysis

- time complexity `O(nlogn)`
- space complexity `O(1)`