Submission #1268622

#	Time	Username	Problem	Language	Result	Execution time	Memory
1268622		MisterReaper	Flooding Wall (BOI24_wall)	C++20	70 / 100	5087 ms	14148 KiB

Main

// File A.cpp created on 10.09.2025 at 12:56:52
#include <bits/stdc++.h>

using i64 = long long;

#ifdef DEBUG 
    #include "/home/ahmetalp/Desktop/Workplace/debug.h"
#else
    #define debug(...) void(23)
#endif

template<typename T>
T power(T a, i64 b) {
    T res {1};
    while (b) {
        if (b & 1) {
            res *= a;
        }
        a *= a;
        b >>= 1;
    }
    return res;
}

constexpr int md = int(1E9) + 7;
struct MInt {
    int val;
    MInt() : val(0) {}
    template<typename T>
    MInt(T x) {
        if (-md <= x && x < md) {
            val = x; 
        } else {
            val = x % md;
        }
        if (val < 0) {
            val += md;
        }
    }
    int operator()() { return val; }
    MInt& operator+= (MInt rhs) {
        if ((val += rhs.val) >= md) {
            val -= md;
        }
        return *this;
    }
    MInt& operator-= (MInt rhs) {
        if ((val -= rhs.val) < 0) {
            val += md;
        }
        return *this;
    }
    MInt& operator*= (MInt rhs) {
        val = int(1LL * val * rhs.val % md);
        return *this;
    }
    MInt inv() {
        return power(*this, md - 2);
    }
    MInt& operator/= (MInt rhs) {
        return *this *= rhs.inv();
    }
    bool operator== (MInt rhs) const {
        return val == rhs.val;
    }
    bool operator!= (MInt rhs) const {
        return val != rhs.val;
    }
};
MInt operator+ (MInt lhs, MInt rhs) {
    return lhs += rhs;
}
MInt operator- (MInt lhs, MInt rhs) {
    return lhs -= rhs;
}
MInt operator* (MInt lhs, MInt rhs) {
    return lhs *= rhs;
}
MInt operator/ (MInt lhs, MInt rhs) {
    return lhs /= rhs;
}
std::ostream& operator<< (std::ostream& os, MInt x) {
    return os << x.val;
}
std::string to_string(MInt x) {
    return to_string(x.val);
}

using Z = MInt;

int main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);

    int N;
    std::cin >> N;

    std::vector<int> A(N), B(N);
    for (int i = 0; i < N; ++i) {
        std::cin >> A[i];
    }
    for (int i = 0; i < N; ++i) {
        std::cin >> B[i];
    }

    std::vector<Z> pow2(N + 1);
    pow2[0] = 1;
    for (int i = 1; i <= N; ++i) {
        pow2[i] = pow2[i - 1] * 2;
    }

    std::vector<int> nums {0};
    nums.insert(nums.end(), A.begin(), A.end());
    nums.insert(nums.end(), B.begin(), B.end());
    std::sort(nums.begin(), nums.end());
    nums.erase(std::unique(nums.begin(), nums.end()), nums.end());

    int n = int(nums.size());

    Z ans = 0;

    for (int _ = 1; _ < n; ++_) {
        int x = nums[_];
        int dif = nums[_] - nums[_ - 1];
        std::vector<Z> pre(N + 1), suf(N + 1);
        pre[0] = 1;
        for (int i = 0; i < N; ++i) {
            pre[i + 1] = pre[i] * ((A[i] < x) + (B[i] < x));
        }
        suf[N] = 1;
        for (int i = N - 1; i >= 0; --i) {
            suf[i] = suf[i + 1] * ((A[i] < x) + (B[i] < x));
        }
        Z res = 0;
        for (int i = 0; i < N; ++i) {
            res += (pow2[i] - pre[i]) * (pow2[N - i - 1] - suf[i + 1]) * ((A[i] < x) + (B[i] < x));
            res += pow2[N - 1] * ((A[i] >= x) + (B[i] >= x));
        }
        debug(x, res);
        ans += dif * res;
    }

    for (int i = 0; i < N; ++i) {
        ans -= pow2[N - 1] * A[i];
        ans -= pow2[N - 1] * B[i];
    }

    std::cout << ans << '\n';

    return 0;
}

• Subtask 1: 8 / 8
• Subtask 2: 17 / 17
• Subtask 3: 19 / 19
• Subtask 4: 14 / 14
• Subtask 5: 12 / 12
• Subtask 6: 0 / 30