Submission

xPPPPxxxPPPPxxxP

Score: 90

User: Nagornz

Problemset: Chocolate

Language: cpp

Time: 0.320 second

Submitted On: 2025-03-14 21:52:51

#include <bits/stdc++.h>
#define int long long
#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;
const int inf = 1e18;

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;
    map <pii, int> pref;
    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 << i << " -> " << j << ": " << pref[i][j] << "\n";
        }
    }
    vector <vector <int>> dp(k + 1, vector <int> (n + 1));
    // 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++) {
        for (int j = 1; j <= n; j++) {
            dp[i - 1][j] += dp[i - 1][j - 1];
        }
        for (int j = i; j <= n; j++) {
            int l = 1, r = j;
            int lidx = 0;
            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;
            int ridx = 0;
            while (l <= r) {
                int mid = (l + r) / 2;
                if (pref[{mid, j}] >= ll) {
                    l = mid + 1;
                    ridx = mid;
                } 
                else r = mid - 1;
            }
            // cout << j << ": " << lidx << ", " << ridx << "\n";
            dp[i][j] = (ridx - 1 < 0 ? 0 : dp[i - 1][ridx - 1]) - (lidx == 0 ? 1e14 : (lidx == 1 ? 0 : dp[i - 1][lidx - 2]));
            // cout << i << ", " << j << ": " << dp[i][j] << "\n------------\n";
            dp[i][j] %= mod;
        }
    }
    cout << max(0ll, dp[k][n]);
}