Submission #1267351

#	Time	Username	Problem	Language	Result	Execution time	Memory
1267351		MisterReaper	Election (BOI18_election)	C++17	100 / 100	247 ms	20948 KiB

election

// File A.cpp created on 05.09.2025 at 19:26:11
#include <bits/stdc++.h>

using i64 = long long;

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

struct node {
    int pre, suf, sum, ans;
    node() : pre(0), suf(0), sum(0), ans(0) {}
    node(int x) : pre(std::max(0, x)), suf(std::max(0, x)), sum(x), ans(std::max(0, x)) {}
};
node operator+ (node lhs, node rhs) {
    node res;
    res.pre = std::max(lhs.pre, rhs.pre + lhs.sum);
    res.suf = std::max(rhs.suf, lhs.suf + rhs.sum);
    res.sum = lhs.sum + rhs.sum;
    res.ans = std::max({lhs.pre + rhs.suf, lhs.ans + rhs.sum, rhs.ans + lhs.sum});
    return res;
}

#define def int mid = (l + r) >> 1, lv = v + 1, rv = v + ((mid - l + 1) << 1)
struct segtree {
    int n;
    std::vector<node> tree;
    segtree(std::vector<int>& x) : n(int(x.size())), tree(n << 1) {
        auto dfs = [&](auto&& self, int v, int l, int r) -> void {
            if (l == r) {
                tree[v] = {x[l]};
                return;
            }
            def;
            self(self, lv, l, mid);
            self(self, rv, mid + 1, r);
            tree[v] = tree[lv] + tree[rv];
        };
        dfs(dfs, 0, 0, n - 1);
    }
    node get(int v, int l, int r, int ql, int qr) {
        if (ql == l && r == qr) {
            return tree[v];
        }
        def;
        if (qr <= mid) {
            return get(lv, l, mid, ql, qr); 
        } else if (mid + 1 <= ql) {
            return get(rv, mid + 1, r, ql, qr);
        } else {
            return get(lv, l, mid, ql, mid)
                + get(rv, mid + 1, r, mid + 1, qr);
        }
    }
    node get(int l, int r) {
        return get(0, 0, n - 1, l, r);
    }
};

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

    int N;
    std::cin >> N;

    std::vector<int> A(N);
    for (int i = 0; i < N; ++i) {
        char c;
        std::cin >> c;
        A[i] = c == 'C' ? -1 : +1;
    }

    segtree seg(A);

    int Q;
    std::cin >> Q;

    while (Q--) {
        int L, R;
        std::cin >> L >> R;
        --L, --R;

        node nd = seg.get(L, R);
        std::cout << nd.ans << '\n';
    }

    return 0;
}

• Subtask 1: 28 / 28
• Subtask 2: 54 / 54
• Subtask 3: 18 / 18