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IDProblemSubmitterResultTimeMemoryLanguageFile sizeSubmit timeJudge time
#212962#6346. Record ParityhappypotatoWA 23ms50744kbC++141.2kb2023-10-13 23:54:222023-10-13 23:54:22

Judging History

你现在查看的是最新测评结果

  • [2023-10-13 23:54:22]
  • 评测
  • 测评结果:WA
  • 用时:23ms
  • 内存:50744kb
  • [2023-10-13 23:54:22]
  • 提交

answer

#include <bits/stdc++.h>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>
#define int long long
#define double long double
#define x first
#define y second
#define pb push_back
using namespace std;
using namespace __gnu_pbds;
using pii=pair <int,int>;
using tii=pair <pii,int>;
using rii=pair <int,pii>;
using qii=pair <pii,pii>;
const int mod=998244353LL;
int f[2000010],inv[2000010],finv[2000010];
void init(){
    f[0]=f[1]=inv[0]=inv[1]=finv[0]=finv[1]=1;
    for (int i=2; i<2000010; i++){
        f[i]=f[i-1]*i%mod;
        inv[i]=inv[mod%i]*(mod-mod/i)%mod;
        finv[i]=finv[i-1]*inv[i]%mod;
    }
}
int ncr(int n,int r){
    if (n<r) return 0;
    return f[n]*finv[n-r]%mod*finv[r]%mod;
}
void solve(){
    int n,k;
    cin>>n>>k;
    int p[n+1];
    for (int i=1; i<=n; i++) cin>>p[i];
    vector <int> v;
    v.pb(1);
    for (int i=2; i<=n; i++){
        if (p[i-1]>p[i]) v.pb(1);
        else v.back()++;
    }
    int ans=0;
    for (int i:v){
        ans+=ncr(i,k);
        ans%=mod;
    }
    if (k&1) ans=(mod-ans)%mod;
    cout<<ans<<'\n';
}
signed main(){
    ios_base::sync_with_stdio(0); cin.tie(0);
    int t=1;
    //cin>>t;
    init();
    while (t--) solve();
}

Details

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Test #1:

score: 100
Accepted
time: 11ms
memory: 50460kb

input:

5 2
4 1 2 5 3

output:

3

result:

ok 1 number(s): "3"

Test #2:

score: 0
Accepted
time: 17ms
memory: 50744kb

input:

7 3
1 2 3 4 5 6 7

output:

998244318

result:

ok 1 number(s): "998244318"

Test #3:

score: 0
Accepted
time: 22ms
memory: 50524kb

input:

5 5
2 5 4 1 3

output:

0

result:

ok 1 number(s): "0"

Test #4:

score: -100
Wrong Answer
time: 23ms
memory: 50440kb

input:

10 3
9 7 3 6 10 4 8 2 5 1

output:

998244352

result:

wrong answer 1st numbers differ - expected: '0', found: '998244352'