Submission #1832327

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Source Code Expand

#include <bits/stdc++.h>

#define fr first
#define sc second
#define OK puts("OK");
#define pb push_back
#define mk make_pair

using namespace std;

typedef long long ll;

const ll inf = (ll)1e18 + 7;
const int N = (int)2e6 + 7;

ll n,a;
ll mn = inf;
ll u[N];

void bfs (int v) {
        queue <pair<int,pair<int,ll> > > q;

        q.push({v,{1,1ll}});

        while (!q.empty()) {
                int v = q.front().fr,d = q.front().sc.fr;
                ll t = q.front().sc.sc;

                q.pop();

                if (v >= n) {
                        mn = min(mn,t);
                        continue;
                }
                if (u[v] < t || t > v)
                        continue;
                u[v] = t;

                if (t + 1 <= v + d)
                        q.push({v + d,{d,t + 1}});
                if (t + a + 2 <= v + v)
                        q.push({v + v,{v,t + a + 2}});
        }
}
 main () {
        cin >> n >> a;

        for (int i = 1; i <= 1e6; i ++)
                u[i] = inf;

        u[1] = 1;

        bfs(1);

        cout << mn << endl;
}

Submission Info

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