Submission #1115328

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Source Code Expand

#include "bits/stdc++.h"
using namespace std;
#ifdef _DEBUG
#include "dump.hpp"
#else
#define dump(...)
#endif

#define int long long
#define rep(i,a,b) for(int i=(a);i<(b);i++)
#define rrep(i,a,b) for(int i=(b)-1;i>=(a);i--)
#define all(c) begin(c),end(c)
const int INF = sizeof(int) == sizeof(long long) ? 0x3f3f3f3f3f3f3f3fLL : 0x3f3f3f3f;
const int MOD = (int)(1e9) + 7;
template<class T> bool chmax(T &a, const T &b) { if (a < b) { a = b; return true; } return false; }
template<class T> bool chmin(T &a, const T &b) { if (a > b) { a = b; return true; } return false; }

int N, M;
bool f(int x) {
	if (M - (x - N) * 2 >= 2 * x)return false;
	else return true;
}

template<class F>
int binary_search_(int l, int r, F f) {
	if (f(l))return l; //exception f(l):true
	while (l + 1 < r) {
		int m = (l + r) / 2;
		if (f(m))
			r = m;
		else
			l = m;
	}
	//f(l):false, f(r):true
	return r;
}

signed main() {
	cin.tie(0);
	ios::sync_with_stdio(false);
	cin >> N >> M;
	int a = binary_search_(N, 1e12 + 1, f);
	dump(f(a), f(a - 1));
	if (f(a) == false)cout << a << endl;
	else cout << a - 1 << endl;
	return 0;
}

Submission Info

Judge Result