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IDProblemSubmitterResultTimeMemoryLanguageFile sizeSubmit timeJudge time
#472320#6417. Classical Summation Problemlllei#AC ✓238ms11764kbC++201.1kb2024-07-11 15:39:422024-07-11 15:39:42

Judging History

你现在查看的是最新测评结果

  • [2024-07-11 15:39:42]
  • 评测
  • 测评结果:AC
  • 用时:238ms
  • 内存:11764kb
  • [2024-07-11 15:39:42]
  • 提交

answer

#include <bits/stdc++.h>
using namespace std;
const long long mod = 998244353;
long long pw(long long t1, long long t2) {
    long long tmp1 = 1, tmp2 = t1;
    while (t2) {
        if (t2 & 1)
            tmp1 = tmp1 * tmp2 % mod;
        tmp2 = tmp2 * tmp2 % mod;
        t2 /= 2;
    }
    return tmp1;
}
int n, k;
const int maxn=1e6+5;
int fct[maxn],inv[maxn];
int c(int x,int y)
{
    return fct[x]*1ll*inv[x-y]%mod*inv[y]%mod;
}
int main() {
    scanf("%d%d", &n, &k);
    fct[0]=inv[0]=1;
    for(int i=1;i<=k;i++)fct[i]=fct[i-1]*1ll*i%mod,inv[i]=pw(fct[i],mod-2);
    if (k & 1) {
        printf("%d\n", pw(n, k) * 1LL * (n + 1) % mod * pw(2, mod - 2) % mod);
    } else {
        int ans = 0;
        for (int i = 1; i < n; i++) {
            ans += pw(i, k / 2) * 1LL * pw(n - i, k / 2) % mod*c(k,k/2)%mod;
            ans %=mod;
        }
        ans = ans * 1LL * pw(pw(n,k), mod - 2)%mod;
        //cout<<ans<<endl;
        ans = ((n + 1) * 1LL * pw(2, mod - 2) % mod - ans * 1LL * pw(2, mod - 2) % mod + mod) % mod;
        ans = ans*1LL*pw(n, k)%mod;
        printf("%d\n", ans);
    }
}

Details

Tip: Click on the bar to expand more detailed information

Test #1:

score: 100
Accepted
time: 1ms
memory: 5864kb

input:

3 2

output:

14

result:

ok 1 number(s): "14"

Test #2:

score: 0
Accepted
time: 0ms
memory: 6008kb

input:

5 3

output:

375

result:

ok 1 number(s): "375"

Test #3:

score: 0
Accepted
time: 0ms
memory: 5952kb

input:

2 2

output:

5

result:

ok 1 number(s): "5"

Test #4:

score: 0
Accepted
time: 0ms
memory: 6004kb

input:

10 9

output:

508778235

result:

ok 1 number(s): "508778235"

Test #5:

score: 0
Accepted
time: 1ms
memory: 5952kb

input:

69 3

output:

11497815

result:

ok 1 number(s): "11497815"

Test #6:

score: 0
Accepted
time: 1ms
memory: 5880kb

input:

994 515

output:

33689623

result:

ok 1 number(s): "33689623"

Test #7:

score: 0
Accepted
time: 2ms
memory: 5984kb

input:

4476 6182

output:

114894183

result:

ok 1 number(s): "114894183"

Test #8:

score: 0
Accepted
time: 2ms
memory: 5952kb

input:

58957 12755

output:

932388891

result:

ok 1 number(s): "932388891"

Test #9:

score: 0
Accepted
time: 22ms
memory: 6044kb

input:

218138 28238

output:

392861201

result:

ok 1 number(s): "392861201"

Test #10:

score: 0
Accepted
time: 100ms
memory: 7140kb

input:

644125 316810

output:

420621854

result:

ok 1 number(s): "420621854"

Test #11:

score: 0
Accepted
time: 124ms
memory: 10772kb

input:

612914 505428

output:

973686286

result:

ok 1 number(s): "973686286"

Test #12:

score: 0
Accepted
time: 101ms
memory: 11616kb

input:

998216 938963

output:

251335926

result:

ok 1 number(s): "251335926"

Test #13:

score: 0
Accepted
time: 111ms
memory: 11692kb

input:

990516 996933

output:

549551960

result:

ok 1 number(s): "549551960"

Test #14:

score: 0
Accepted
time: 231ms
memory: 11584kb

input:

999019 999012

output:

637189128

result:

ok 1 number(s): "637189128"

Test #15:

score: 0
Accepted
time: 236ms
memory: 11700kb

input:

999928 999950

output:

185229465

result:

ok 1 number(s): "185229465"

Test #16:

score: 0
Accepted
time: 111ms
memory: 11704kb

input:

999999 999999

output:

384164916

result:

ok 1 number(s): "384164916"

Test #17:

score: 0
Accepted
time: 229ms
memory: 11728kb

input:

999999 1000000

output:

696165930

result:

ok 1 number(s): "696165930"

Test #18:

score: 0
Accepted
time: 107ms
memory: 11624kb

input:

1000000 999999

output:

219071706

result:

ok 1 number(s): "219071706"

Test #19:

score: 0
Accepted
time: 229ms
memory: 11660kb

input:

1000000 1000000

output:

128206597

result:

ok 1 number(s): "128206597"

Test #20:

score: 0
Accepted
time: 0ms
memory: 5996kb

input:

2 10

output:

1410

result:

ok 1 number(s): "1410"

Test #21:

score: 0
Accepted
time: 0ms
memory: 5960kb

input:

84 16

output:

297627153

result:

ok 1 number(s): "297627153"

Test #22:

score: 0
Accepted
time: 1ms
memory: 6000kb

input:

643 800

output:

489237163

result:

ok 1 number(s): "489237163"

Test #23:

score: 0
Accepted
time: 1ms
memory: 5948kb

input:

9903 880

output:

595167333

result:

ok 1 number(s): "595167333"

Test #24:

score: 0
Accepted
time: 21ms
memory: 6348kb

input:

97446 89750

output:

410205549

result:

ok 1 number(s): "410205549"

Test #25:

score: 0
Accepted
time: 86ms
memory: 11060kb

input:

186460 646474

output:

32638530

result:

ok 1 number(s): "32638530"

Test #26:

score: 0
Accepted
time: 83ms
memory: 6856kb

input:

508940 244684

output:

598321755

result:

ok 1 number(s): "598321755"

Test #27:

score: 0
Accepted
time: 125ms
memory: 10548kb

input:

583646 557758

output:

858695621

result:

ok 1 number(s): "858695621"

Test #28:

score: 0
Accepted
time: 224ms
memory: 11676kb

input:

969610 992608

output:

256683498

result:

ok 1 number(s): "256683498"

Test #29:

score: 0
Accepted
time: 233ms
memory: 11688kb

input:

995106 996434

output:

411791999

result:

ok 1 number(s): "411791999"

Test #30:

score: 0
Accepted
time: 230ms
memory: 11720kb

input:

999961 999872

output:

61222370

result:

ok 1 number(s): "61222370"

Test #31:

score: 0
Accepted
time: 233ms
memory: 11764kb

input:

999977 999908

output:

831096762

result:

ok 1 number(s): "831096762"

Test #32:

score: 0
Accepted
time: 238ms
memory: 11636kb

input:

999992 999998

output:

562977678

result:

ok 1 number(s): "562977678"

Test #33:

score: 0
Accepted
time: 8ms
memory: 5952kb

input:

1000000 2

output:

118436113

result:

ok 1 number(s): "118436113"

Test #34:

score: 0
Accepted
time: 107ms
memory: 11640kb

input:

2 1000000

output:

298823641

result:

ok 1 number(s): "298823641"