760B - Frodo and pillows - CodeForces Solution

#include<bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>

using namespace std;
using namespace __gnu_pbds;
template<class T> using ordered_set = tree<T, null_type, less<T>, rb_tree_tag,tree_order_statistics_node_update>;

#define ll long long
#define pb push_back
#define FOR(n) for (int i = 0; i < n; i++)
#define FORj(n) for (int j = 0; j < n; j++)

void solve() {
    int n, m, k;cin >> n >> m >> k;

    int l = k, r = k;

    int ans = 1;
    m -= n;

    while (m >= (r - l + 1)) {
        ans++;
        m -= (r - l + 1);
        r = min(r + 1, n);
        l = max(l - 1, 1 );

        if (l == 1 && r == n) break;
    }

    ans += (m / n);

    cout << ans;
}

int main () {
    ios::sync_with_stdio(0); cin.tie(0);
    int T = 1;
    //cin >> T;
    while (T--) solve();
    return 0;
}