Submission #136695

#	Time	Username	Problem	Language	Result	Execution time	Memory
136695		choikiwon	A Huge Tower (CEOI10_tower)	C++17	85 / 100	1067 ms	18552 KiB

tower

#include<bits/stdc++.h>
using namespace std;

const int mod = 1e9 + 9;

int N, D;
vector<int> fact, A, B;
vector<int> dp[2];

int main() {
    scanf("%d %d", &N, &D);

    fact.resize(N + 1);
    fact[0] = 1;
    for(int i = 1; i <= N; i++) {
        fact[i] = 1LL * fact[i - 1] * i % mod;
    }

    A.resize(N);
    for(int i = 0; i < N; i++) {
        scanf("%d", &A[i]);
    }

    sort(A.begin(), A.end());

    B.resize(N);
    int pos = N - 1;
    for(int i = N - 1; i >= 0; i--) {
        while(pos >= 0 && A[pos] > A[i] + D) pos--;
        B[i] = N - 1 - pos;
    }

    dp[0] = dp[1] = vector<int>(N);

    for(int i = 0; i < N; i++) {
        dp[1][i] = i % 2? mod - fact[N - i] : fact[N - i];
    }
    for(int i = 0; i < N; i++) {
        int c = i & 1;
        int p = c ^ 1;
        for(int j = 0; j < N; j++) {
            int &ret = dp[c][j] = 0;
            ret += dp[p][j];
            ret %= mod;
            if(B[i] > j) {
                ret += 1LL * dp[p][j + 1] * (B[i] - j) % mod;
                ret %= mod;
            }
        }
    }
    printf("%d", dp[(N - 1) & 1][0]);
}

Compilation message (stderr)

tower.cpp: In function 'int main()':
tower.cpp:11:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d %d", &N, &D);
     ~~~~~^~~~~~~~~~~~~~~~~
tower.cpp:21:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d", &A[i]);
         ~~~~~^~~~~~~~~~~~~

• Subtask 1: 5 / 5
• Subtask 2: 5 / 5
• Subtask 3: 5 / 5
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• Subtask 18: 0 / 5
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