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#155632#6417. Classical Summation ProblemForever_Young#AC ✓186ms3716kbC++141004b2023-09-01 22:22:482023-09-01 22:22:48

Judging History

你现在查看的是最新测评结果

  • [2023-09-01 22:22:48]
  • 评测
  • 测评结果：AC
  • 用时：186ms
  • 内存：3716kb
查看
  • [2023-09-01 22:22:48]
  • 提交

answer

#include<bits/stdc++.h>
using namespace std;
typedef long long LL;
const LL mod = 998244353;
LL fastpo(LL x, LL n, LL mod) {
	x %= mod;
	LL res = 1;
	while(n) {
		if(n % 2 == 1) {
			res = (res * x) % mod;
		}
		x = x * x % mod;
		n /= 2;
	}
	return res;
}
int main() {
	LL n, k;
	cin >> n >> k;
	LL inv2 = (mod + 1) / 2;
	LL ans = 0;
	if(k % 2 == 1) {
		ans = fastpo(n, k, mod);
		ans = (ans * (1 + n)) % mod;
		ans = ans * inv2 % mod;
	}else {
		ans = fastpo(n, k, mod);
		ans = (ans * (1 + n)) % mod;
		ans = ans * inv2 % mod;
		LL tmp = 0;
		LL ck = 1;
		for(int i = 1; i <= k / 2; i++) {
			ck = (ck * fastpo(i, mod - 2, mod)) % mod;
			ck = ck * (k - i + 1) % mod;
		}
		for(int j = 1; j <= n - 1; j++) {
			tmp = tmp + ck * fastpo(j, k / 2, mod) % mod * fastpo(n - j, k / 2, mod);
			tmp = tmp % mod;
		}
		tmp = tmp * inv2 % mod;
		//cout << ans << ' ' << tmp << endl;
		ans = (ans - tmp) % mod;
		ans = (ans + mod) % mod;
	}
	cout << ans << endl;
}
源文件, 语言: C++14

详细

Test #1:

score: 100
Accepted
time: 1ms
memory: 3620kb

input:

3 2

output:

14

result:

ok 1 number(s): "14"

Test #2:

score: 0
Accepted
time: 1ms
memory: 3648kb

input:

5 3

output:

375

result:

ok 1 number(s): "375"

Test #3:

score: 0
Accepted
time: 1ms
memory: 3520kb

input:

2 2

output:

5

result:

ok 1 number(s): "5"

Test #4:

score: 0
Accepted
time: 1ms
memory: 3516kb

input:

10 9

output:

508778235

result:

ok 1 number(s): "508778235"

Test #5:

score: 0
Accepted
time: 1ms
memory: 3556kb

input:

69 3

output:

11497815

result:

ok 1 number(s): "11497815"

Test #6:

score: 0
Accepted
time: 1ms
memory: 3700kb

input:

994 515

output:

33689623

result:

ok 1 number(s): "33689623"

Test #7:

score: 0
Accepted
time: 2ms
memory: 3648kb

input:

4476 6182

output:

114894183

result:

ok 1 number(s): "114894183"

Test #8:

score: 0
Accepted
time: 1ms
memory: 3644kb

input:

58957 12755

output:

932388891

result:

ok 1 number(s): "932388891"

Test #9:

score: 0
Accepted
time: 22ms
memory: 3632kb

input:

218138 28238

output:

392861201

result:

ok 1 number(s): "392861201"

Test #10:

score: 0
Accepted
time: 90ms
memory: 3640kb

input:

644125 316810

output:

420621854

result:

ok 1 number(s): "420621854"

Test #11:

score: 0
Accepted
time: 104ms
memory: 3632kb

input:

612914 505428

output:

973686286

result:

ok 1 number(s): "973686286"

Test #12:

score: 0
Accepted
time: 1ms
memory: 3668kb

input:

998216 938963

output:

251335926

result:

ok 1 number(s): "251335926"

Test #13:

score: 0
Accepted
time: 1ms
memory: 3716kb

input:

990516 996933

output:

549551960

result:

ok 1 number(s): "549551960"

Test #14:

score: 0
Accepted
time: 185ms
memory: 3516kb

input:

999019 999012

output:

637189128

result:

ok 1 number(s): "637189128"

Test #15:

score: 0
Accepted
time: 181ms
memory: 3516kb

input:

999928 999950

output:

185229465

result:

ok 1 number(s): "185229465"

Test #16:

score: 0
Accepted
time: 1ms
memory: 3644kb

input:

999999 999999

output:

384164916

result:

ok 1 number(s): "384164916"

Test #17:

score: 0
Accepted
time: 181ms
memory: 3552kb

input:

999999 1000000

output:

696165930

result:

ok 1 number(s): "696165930"

Test #18:

score: 0
Accepted
time: 1ms
memory: 3588kb

input:

1000000 999999

output:

219071706

result:

ok 1 number(s): "219071706"

Test #19:

score: 0
Accepted
time: 181ms
memory: 3512kb

input:

1000000 1000000

output:

128206597

result:

ok 1 number(s): "128206597"

Test #20:

score: 0
Accepted
time: 1ms
memory: 3556kb

input:

2 10

output:

1410

result:

ok 1 number(s): "1410"

Test #21:

score: 0
Accepted
time: 1ms
memory: 3644kb

input:

84 16

output:

297627153

result:

ok 1 number(s): "297627153"

Test #22:

score: 0
Accepted
time: 1ms
memory: 3636kb

input:

643 800

output:

489237163

result:

ok 1 number(s): "489237163"

Test #23:

score: 0
Accepted
time: 1ms
memory: 3568kb

input:

9903 880

output:

595167333

result:

ok 1 number(s): "595167333"

Test #24:

score: 0
Accepted
time: 16ms
memory: 3644kb

input:

97446 89750

output:

410205549

result:

ok 1 number(s): "410205549"

Test #25:

score: 0
Accepted
time: 59ms
memory: 3692kb

input:

186460 646474

output:

32638530

result:

ok 1 number(s): "32638530"

Test #26:

score: 0
Accepted
time: 73ms
memory: 3572kb

input:

508940 244684

output:

598321755

result:

ok 1 number(s): "598321755"

Test #27:

score: 0
Accepted
time: 97ms
memory: 3652kb

input:

583646 557758

output:

858695621

result:

ok 1 number(s): "858695621"

Test #28:

score: 0
Accepted
time: 178ms
memory: 3712kb

input:

969610 992608

output:

256683498

result:

ok 1 number(s): "256683498"

Test #29:

score: 0
Accepted
time: 184ms
memory: 3648kb

input:

995106 996434

output:

411791999

result:

ok 1 number(s): "411791999"

Test #30:

score: 0
Accepted
time: 181ms
memory: 3568kb

input:

999961 999872

output:

61222370

result:

ok 1 number(s): "61222370"

Test #31:

score: 0
Accepted
time: 184ms
memory: 3556kb

input:

999977 999908

output:

831096762

result:

ok 1 number(s): "831096762"

Test #32:

score: 0
Accepted
time: 186ms
memory: 3632kb

input:

999992 999998

output:

562977678

result:

ok 1 number(s): "562977678"

Test #33:

score: 0
Accepted
time: 9ms
memory: 3644kb

input:

1000000 2

output:

118436113

result:

ok 1 number(s): "118436113"

Test #34:

score: 0
Accepted
time: 56ms
memory: 3636kb

input:

2 1000000

output:

298823641

result:

ok 1 number(s): "298823641"
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