Submission #74120913

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Source Code Expand

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

int main() {
    ll L, R, D, U;
    cin >> L >> R >> D >> U;

    ll ans = 0;
    // 原点
    if (0 >= L && 0 <= R && 0 >= D && 0 <= U) ans++;

    ll M = max({abs(L), abs(R), abs(D), abs(U)});
    for (ll k = 2; k <= M; k += 2) {
        // 上边 y = k
        if (D <= k && k <= U) {
            ll left = max(L, -k);
            ll right = min(R, k);
            if (left <= right) ans += right - left + 1;
        }
        // 下边 y = -k
        if (D <= -k && -k <= U) {
            ll left = max(L, -k);
            ll right = min(R, k);
            if (left <= right) ans += right - left + 1;
        }
        // 左边 x = -k
        if (L <= -k && -k <= R) {
            ll low = max(D, -k + 1);
            ll high = min(U, k - 1);
            if (low <= high) ans += high - low + 1;
        }
        // 右边 x = k
        if (L <= k && k <= R) {
            ll low = max(D, -k + 1);
            ll high = min(U, k - 1);
            if (low <= high) ans += high - low + 1;
        }
    }

    cout << ans << endl;
    return 0;
}

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