Submission #677630

#	Time	Username	Problem	Language	Result	Execution time	Memory
677630		jhwest2	Remittance (JOI19_remittance)	C++14	100 / 100	254 ms	36436 KiB

remittance

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

typedef long long ll;
const int N = 1010101;
const ll INF = 1e13 + 10;

int n; ll a[N], b[N];
int main() {
    cin.tie(0); ios_base::sync_with_stdio(0);
    cin >> n;
    bool f = false, g = false;
    for (int i = 0; i < n; i++) {
        ll x, y; cin >> x >> y;
        if (x)
            f = true;
        if (y)
            g = true;
        a[i] = b[i] = x - y;
    }
    if (!g) {
        if (!f)
            cout << "Yes";
        else
            cout << "No";
        return 0;
    }
    ll L = -1, R = 2e9 + 10;
    while (L < R) {
        ll M = (L + R) >> 1;
        for (int i = 0; i < n; i++)
            a[i] = b[i];

        int r = 0;
        for (int i = n - 1; i > 0; i--) {
            ll d = M - a[i];
            a[i] += d;
            a[i - 1] -= 2 * d;

            if (a[i - 1] < -INF) {
                r = 1;
                break;
            }
            if (a[i - 1] > INF) {
                r = 2;
                break;
            }
        }
        if (r == 1)
            R = M;
        else if (r == 2)
            L = M + 1;
        else {
            if (a[0] <= M)
                R = M;
            else
                L = M + 1;
        }
    }
    for (int i = 0; i < n; i++)
        a[i] = b[i];

    for (int i = n - 1; i > 0; i--) {
        ll d = L - a[i];
        a[i] += d;
        a[i - 1] -= 2 * d;

        if (a[i - 1] < -INF || a[i - 1] > INF) {
            return !(cout << "No");
        }
    }
    if (a[0] != L)
        return !(cout << "No");
    
    for (int i = n - 1; i >= 0; i--) {
        L = 2 * L - b[i];
        if (L < 0)
            return !(cout << "No");
    }
    cout << "Yes";
}

• Subtask 1: 15 / 15
• Subtask 2: 40 / 40
• Subtask 3: 45 / 45