Submission #607302

#	Time	Username	Problem	Language	Result	Execution time	Memory
607302		kawaii	Skyscraper (JOI16_skyscraper)	C++14	100 / 100	370 ms	130172 KiB

skyscraper

#include <bits/stdc++.h>
using namespace std;
#define int long long
#define fi first
#define se second

int t, n, l, m, k, a[1000005], dp[105][105][1005][3], mod = 1e9 + 7;
string s;
mt19937_64 rng;

int mul(int x, int y){
    if(y == 0) return 1;
    int ans = mul(x, y / 2);
    if(y % 2 == 0) return (ans * ans) % mod;
    else return (((ans * ans) % mod) * x) % mod;
}

void solve(){
    if(n == 1){
        cout << 1; return;
    }
    sort(a + 1, a + n + 1);
    dp[0][0][0][0] = 1;
    for(int i = 1; i <= n; i++){
        // for each i, set some ? to a[i] and calculate the sum abs
        for(int j = 1; j <= n; j++){
            int diff = a[i] - a[i - 1], upd = 0;
            for(int sum = 0; sum <= l; sum++){
                for(int k = 0; k <= 2; k++){
                    if(k >= 1){ // add an endpoint to front or back
                        // before add an endpoint there are k - 1 endpoints
                        // because there are j - 1 component before add a point -> need to add (j - 1) * 2 (OSU)
                        upd = diff * ((j - 1) * 2 - (k - 1)); //  create new component
                        if(sum >= upd) dp[i][j][sum][k] = (dp[i][j][sum][k] + (2 - (k - 1)) * dp[i - 1][j - 1][sum - upd][k - 1]) % mod;
                        // Similarly to (OSU) -> need to add j * 2
                        upd = diff * (j * 2 - (k - 1)); // add at the begin or end of an exist component
                        if(sum >= upd) dp[i][j][sum][k] = (dp[i][j][sum][k] + (2 - (k - 1)) * dp[i - 1][j][sum - upd][k - 1]) % mod;
                    }
                    // add a point to somewhere different
                    // because there are j component after add a point -> need to -1, 0, +1 in different case
                    upd = diff * ((j - 1) * 2 - k); // create new component
                    if(sum >= upd) dp[i][j][sum][k] = (dp[i][j][sum][k] + ((j - 1) + 1 - k) * dp[i - 1][j - 1][sum - upd][k]) % mod;
                    upd = diff * ((j + 0) * 2 - k); // add at the begin or end of an exist component
                    if(sum >= upd) dp[i][j][sum][k] = (dp[i][j][sum][k] + ((j + 0) * 2 - k) * dp[i - 1][j][sum - upd][k]) % mod;
                    upd = diff * ((j + 1) * 2 - k); // merge two component 
                    if(sum >= upd) dp[i][j][sum][k] = (dp[i][j][sum][k] + ((j + 1) - 1) * dp[i - 1][j + 1][sum - upd][k]) % mod;
                }
            }
        }
    }
    int ans = 0;
    for(int i = 0; i <= l; i++) ans = (ans + dp[n][1][i][2]) % mod;
    cout << ans;
}

signed main(){
    ios_base::sync_with_stdio(NULL); cin.tie(nullptr); cout.tie(nullptr);
    rng.seed((int)main ^ time(0));
    #ifdef Kawaii
        auto starttime = chrono::high_resolution_clock::now();
    #endif

    cin >> n >> l;
    for(int i = 1; i <= n; i++) cin >> a[i];
    solve();

    #ifdef Kawaii
        auto endtime = chrono::high_resolution_clock::now();
        auto duration = chrono::duration_cast<chrono::milliseconds>(endtime - starttime).count(); 
        cout << "\n=====" << "\nUsed: " << duration << " ms\n";
    #endif
}

• Subtask 1: 5 / 5
• Subtask 2: 15 / 15
• Subtask 3: 80 / 80