AtCoder Beginner Contest 093

C

由于只能加不能减，因此只需要变成3*p即可，但是如果奇偶性不同的话就只能变成3*(p+1)了

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// LUOGU_RID: 174607684
#include <bits/stdc++.h>
using namespace std;

int a, b, c;
int main()
{
    cin >> a >> b >> c;
    int p = max(a, max(b, c));
    int num = p - a + p - b + p - c;
    if (num & 1)
    {
        cout << ((num + 3) >> 1) << '\n';
    }
    else
    {
        cout << (num >> 1) << '\n';
    }
}

D

二分答案，注意判断边界。

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#include <bits/stdc++.h>
using namespace std;
typedef long long LL;
int Q;
LL a, b;
LL LLsqrt(LL x)
{
    LL L = 0, R = 1e9, mid, ans = -1;
    while (L <= R)
    {
        mid = (L + R) >> 1;
        if (mid * mid <= x)
            L = mid + 1, ans = mid;
        else
            R = mid - 1;
    }
    return ans;
}
int main()
{
    cin >> Q;
    while (Q--)
    {
        cin >> a >> b;
        if (a > b)
            swap(a, b);
        LL c = a * b - 1;
        LL d = LLsqrt(c);
        LL ans = d + d;
        if (a != b)
            ans--;
        if (d != 0)
            if (d == c / d)
                ans--;
        cout << max(ans, 0LL) << '\n';
    }
    return 0;
}