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ID | 题目 | 提交者 | 结果 | 用时 | 内存 | 语言 | 文件大小 | 提交时间 | 测评时间 |
---|---|---|---|---|---|---|---|---|---|
#323265 | #8211. Enumerating Substrings | karuna | AC ✓ | 159ms | 7680kb | C++20 | 2.5kb | 2024-02-09 03:11:02 | 2024-02-09 03:11:02 |
Judging History
answer
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int MOD = 1e9 + 7;
struct mint {
int x;
mint() : x(0) {}
mint(int x) : x(x) {}
mint operator+(int ot) const { return x + ot >= MOD ? x + ot - MOD : x + ot; }
mint operator-(int ot) const { return x < ot ? x - ot + MOD : x - ot; }
mint operator*(int ot) const { return 1ll * x * ot % MOD; }
mint operator+=(int ot) { return *this = *this + ot; }
mint operator-=(int ot) { return *this = *this - ot; }
mint operator*=(int ot) { return *this = *this * ot; }
operator int() { return x; }
};
mint mpow(mint a, ll x) {
mint r = 1;
while (x) {
if (x & 1) r *= a;
a *= a;
x /= 2;
}
return r;
}
mint binom(int n, int k) {
mint r = 1;
for (int i = 1; i <= k; i++) r *= i;
r = mpow(r, MOD - 2);
for (int i = n; i > n - k; i--) r *= i;
return r;
}
mint pw[1010101];
int main() {
mint n, m, k;
cin >> n.x >> m.x >> k.x;
pw[0] = 1;
for (int i = 1; i < 1010101; i++) pw[i] = pw[i - 1] * k;
mint ans = 0;
mint acc = 0;
for (int l = (m.x + 1) / 2; l <= m.x; l++) {
if (k.x < m.x - l) continue;
mint cnt = binom(k, m - l);
for (int i = 1; i <= m - l; i++) cnt *= i;
mint tot = 0;
int z = (2 * l - m) / 2;
if (z < l - k.x) {
continue;
}
mint s = binom(k - m + l, z) * binom(k - m + l - z, 2 * l - m - 2 * z) * mpow(2, MOD - 1 - z);
for (int i = 1; i <= 2 * l - m; i++) s *= i;
for (int x = z; x >= 0; x--) {
if (x < l - k.x) continue;
tot += s;
if (x != 0) {
s *= x;
s *= mpow(2 * l - m - 2 * x + 1, MOD - 2);
s *= mpow(2 * l - m - 2 * x + 2, MOD - 2);
s *= (k - l + x);
s *= 2;
}
}
cnt *= tot;
if (l != m.x) {
acc += cnt;
}
else {
cnt -= acc;
}
mint cur = 0;
for (int r = 1; r <= (n.x - m.x + l) / l; r++) {
int sz = r * l + (m.x - l);
int rp = (l == m.x) ? r : (r + 1) / 2;
int sx = 0;
int ex = min(n.x - sz, l - 1);
int sy = max(0, n.x - sz - l + 1);
int ey = n.x - sz;
if (ex < sy) {
cur += pw[n.x - sz - l] * (ex - sx + 1 + ey - sy + 1) * (pw[l] - 1) * rp;
cur += pw[n.x - sz - 2 * l] * (pw[l] - 1) * (pw[l] - 1) * (sy - ex - 1) * rp;
}
else {
cur += pw[n.x - sz - l] * (pw[l] - 1) * (sy - sx + ey - ex) * rp;
cur += pw[n.x - sz] * (ex - sy + 1) * rp;
}
//cout << sz << ' ' << "[" << sx << ", " << ex << "] " << "[" << sy << ", " << ey << "]\n";
}
//cout << l << ' ' << cnt << ' ';
//cout << cur << endl;
ans += cur * cnt;
}
cout << ans << '\n';
}
这程序好像有点Bug,我给组数据试试?
详细
Test #1:
score: 100
Accepted
time: 6ms
memory: 7680kb
input:
4 2 3
output:
228
result:
ok 1 number(s): "228"
Test #2:
score: 0
Accepted
time: 159ms
memory: 7604kb
input:
999999 1999 12345678
output:
52352722
result:
ok 1 number(s): "52352722"
Test #3:
score: 0
Accepted
time: 7ms
memory: 7680kb
input:
7 4 2
output:
182
result:
ok 1 number(s): "182"
Test #4:
score: 0
Accepted
time: 3ms
memory: 7592kb
input:
4 3 4
output:
480
result:
ok 1 number(s): "480"
Test #5:
score: 0
Accepted
time: 3ms
memory: 7596kb
input:
3 1 1
output:
3
result:
ok 1 number(s): "3"
Test #6:
score: 0
Accepted
time: 6ms
memory: 7572kb
input:
5 5 1
output:
0
result:
ok 1 number(s): "0"
Test #7:
score: 0
Accepted
time: 6ms
memory: 7604kb
input:
7 4 3
output:
5784
result:
ok 1 number(s): "5784"
Test #8:
score: 0
Accepted
time: 3ms
memory: 7652kb
input:
5 2 4
output:
3932
result:
ok 1 number(s): "3932"
Test #9:
score: 0
Accepted
time: 6ms
memory: 7604kb
input:
8 2 2
output:
1522
result:
ok 1 number(s): "1522"
Test #10:
score: 0
Accepted
time: 6ms
memory: 7660kb
input:
8 1 2
output:
2048
result:
ok 1 number(s): "2048"
Test #11:
score: 0
Accepted
time: 3ms
memory: 7532kb
input:
7 5 3
output:
2430
result:
ok 1 number(s): "2430"
Test #12:
score: 0
Accepted
time: 7ms
memory: 7540kb
input:
10 4 3
output:
272004
result:
ok 1 number(s): "272004"
Test #13:
score: 0
Accepted
time: 3ms
memory: 7656kb
input:
675978 614 2
output:
0
result:
ok 1 number(s): "0"
Test #14:
score: 0
Accepted
time: 6ms
memory: 7596kb
input:
244613 38 1
output:
0
result:
ok 1 number(s): "0"
Test #15:
score: 0
Accepted
time: 6ms
memory: 7532kb
input:
186293 1462 1
output:
0
result:
ok 1 number(s): "0"
Test #16:
score: 0
Accepted
time: 3ms
memory: 7680kb
input:
24867 886 1
output:
0
result:
ok 1 number(s): "0"
Test #17:
score: 0
Accepted
time: 6ms
memory: 7592kb
input:
976164 1014 2
output:
0
result:
ok 1 number(s): "0"
Test #18:
score: 0
Accepted
time: 6ms
memory: 7600kb
input:
179356 2 716844809
output:
577866092
result:
ok 1 number(s): "577866092"
Test #19:
score: 0
Accepted
time: 14ms
memory: 7672kb
input:
621001 130 310625363
output:
892869197
result:
ok 1 number(s): "892869197"
Test #20:
score: 0
Accepted
time: 37ms
memory: 7548kb
input:
678862 850 754662812
output:
582264789
result:
ok 1 number(s): "582264789"
Test #21:
score: 0
Accepted
time: 46ms
memory: 7656kb
input:
650845 978 348443366
output:
825425732
result:
ok 1 number(s): "825425732"
Test #22:
score: 0
Accepted
time: 16ms
memory: 7536kb
input:
669914 402 87448112
output:
318098088
result:
ok 1 number(s): "318098088"
Test #23:
score: 0
Accepted
time: 26ms
memory: 7600kb
input:
998593 530 681228665
output:
408255654
result:
ok 1 number(s): "408255654"
Test #24:
score: 0
Accepted
time: 138ms
memory: 7604kb
input:
369361 1954 125266115
output:
509912384
result:
ok 1 number(s): "509912384"
Test #25:
score: 0
Accepted
time: 85ms
memory: 7672kb
input:
900226 1378 424079373
output:
406320917
result:
ok 1 number(s): "406320917"
Test #26:
score: 0
Accepted
time: 86ms
memory: 7548kb
input:
334887 1506 17859926
output:
503264679
result:
ok 1 number(s): "503264679"
Test #27:
score: 0
Accepted
time: 30ms
memory: 7592kb
input:
936048 544 53978328
output:
548647866
result:
ok 1 number(s): "548647866"
Test #28:
score: 0
Accepted
time: 60ms
memory: 7668kb
input:
152789 1264 792983073
output:
839541707
result:
ok 1 number(s): "839541707"
Test #29:
score: 0
Accepted
time: 83ms
memory: 7660kb
input:
714493 1392 91796331
output:
721071046
result:
ok 1 number(s): "721071046"
Test #30:
score: 0
Accepted
time: 32ms
memory: 7540kb
input:
269571 816 830801077
output:
330064211
result:
ok 1 number(s): "330064211"
Test #31:
score: 0
Accepted
time: 50ms
memory: 7608kb
input:
845120 944 424581630
output:
348960190
result:
ok 1 number(s): "348960190"
Test #32:
score: 0
Accepted
time: 14ms
memory: 7596kb
input:
533990 368 163586376
output:
522092095
result:
ok 1 number(s): "522092095"
Test #33:
score: 0
Accepted
time: 113ms
memory: 7592kb
input:
181707 1792 462399634
output:
373795106
result:
ok 1 number(s): "373795106"
Test #34:
score: 0
Accepted
time: 134ms
memory: 7660kb
input:
417349 1920 761212891
output:
587051329
result:
ok 1 number(s): "587051329"
Test #35:
score: 0
Accepted
time: 71ms
memory: 7628kb
input:
526583 1344 500217637
output:
108767800
result:
ok 1 number(s): "108767800"
Test #36:
score: 0
Accepted
time: 36ms
memory: 7596kb
input:
867054 769 93998191
output:
239123369
result:
ok 1 number(s): "239123369"
Extra Test:
score: 0
Extra Test Passed