Submission

PP-PP--P----PP--

Score: 70

User: Nagornz

Problemset: Chocolate

Language: cpp

Time: 0.792 second

Submitted On: 2025-03-15 12:34:06

#pragma GCC optimize("Ofast,no-stack-protector,unroll-loops,fast-math,no-stack-protector,inline-small-functions,inline,unsafe-math-optimizations,omit-frame-pointer,inline-functions-called-once")
#include <iostream>
#include <vector>
#pragma GCC target("avx2,fma,popcnt,lzcnt,bmi,bmi2,sse4.2,tune=native")
#define emb emplace_back
#define iShowSpeed cin.tie(NULL)->sync_with_stdio(false)

using namespace std;

const int mod = 1e9 + 7;

const int N = 5005;

int dp[2][N];
int a[N];
vector <int> pref[N];

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

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