Submission

xPPPPx-------P--

Score: 50

User: Nagornz

Problemset: Chocolate

Language: cpp

Time: 0.043 second

Submitted On: 2025-03-15 00:12:34

#include <bits/stdc++.h>
#define double long double
#define pii pair <int,int>
#define tiii tuple <int, int, int>
#define f first
#define s second
#define all(x) x.begin(), x.end()
#define ub(a, b) upper_bound(a.begin(), a.end(), b) - a.begin();
#define lb(a, b) lower_bound(a.begin(), a.end(), b) - a.begin();
#define ve vector
#define graph(a, n) vector <int> a[n];
#define wgraph(a, n) vector <pii> a[n];
#define emb emplace_back
#define em emplace
#define ins insert
#define er erase
#define iShowSpeed cin.tie(NULL)->sync_with_stdio(false)

using namespace std;

template <typename T>
using greater_priority_queue = priority_queue<T, vector<T>, greater<T>>;

const int mod = 1e9 + 7;

int dx[4] = {1, 0, -1, 0};
int dy[4] = {0, 1, 0, -1};

int power(int a, int n){
    int ans = 1;
    while (n) {
        if (n % 2) ans *= a;
        a *= a;
        n /= 2;
    }
    return ans;
}

int32_t main(){
    iShowSpeed;
    int n, k, c; cin >> n >> k >> c;
    vector <int> a(n + 1); for (int i = 1; i <= n; i++) cin >> a[i];
    int ll, rr; cin >> ll >> rr;
    vector <vector <int>> dp(2, vector <int> (n + 1));
    vector <vector <int>> pref(n + 1, vector <int> (n + 1));
    for (int i = 1; i <= n; i++) {
        for (int j = i; j <= n; j++) {
            pref[i][j] = pref[i][j - 1] + a[j] * power(j - i, c);
        }
    }
    // cout << "---------------\n";
    for (int i = 1; i <= n; i++) {
        dp[1][i] = (pref[1][i] >= ll && pref[1][i] <= rr);
        // cout << 1 << ", " << i << ": " << dp[1][i] << "\n";
    }
    // cout << "---------------\n";
    for (int i = 2; i <= k; i++) {
        int curr = i % 2, prev = (i - 1) % 2;
        for (int j = 1; j <= n; j++) {
            dp[prev][j] += dp[prev][j - 1];
        }
        for (int j = 1; j <= n; j++) {
            int l = 1, r = j, lidx = -1, ridx = -1;
            while (l <= r) {
                int mid = (l + r) / 2;
                if (pref[mid][j] <= rr) r = mid - 1, lidx = mid;
                else l = mid + 1;
            }
            l = 1, r = j;
            while (l <= r) {
                int mid = (l + r) / 2;
                if (pref[mid][j] >= ll) l = mid + 1, ridx = mid;
                else r = mid - 1;
            }
            if (ridx == -1 || lidx == -1) dp[curr][j] = 0;
            else {
                dp[curr][j] = dp[prev][ridx - 1] - (lidx == 1 ? 0 : dp[prev][lidx - 2]);
                dp[curr][j] += mod;
                dp[curr][j] %= mod;
            }
        }
        fill(dp[prev].begin(), dp[prev].end(), 0);
    }
    cout << dp[k % 2][n];
}