#include <iostream>
#include <algorithm>
#include <vector>
 
using namespace::std;
 
int nearest(vector<int> a, int x)
{
    auto r = equal_range(a.begin(), a.end(), x);
    if (r.first == a.begin()) return a[0];
    if (r.first == a.end()) return a[a.size() - 1];
    return x - r.first[-1] <= r.first[0] - x ? r.first[-1] : r.first[0];
}
 
int main(void)
{
    vector<int> a = {98, 100, 198, 200, 250, 298};
 
    cout << 50 << " -> " << nearest(a, 50) << endl;
    cout << 195 << " -> " << nearest(a, 195) << endl;
 
    return 0;
}

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