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QOJ
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 |
---|---|---|---|---|---|---|---|---|---|
#86599 | #4807. Melborp Lacissalc | codicon# | WA | 35ms | 19988kb | C++20 | 2.0kb | 2023-03-10 11:44:40 | 2023-03-10 11:44:45 |
Judging History
answer
//
// Created by codicon on 3/9/2023 at 6:56 PM.
//
// The idea is that there is a bijection between the n + 1prefix sums and the n values of the array
#include <bits/stdc++.h>
using namespace std;
# define add(a, b) a = ((a) + (b)) % MOD;
int n, k, t;
const int MAXN = 64, MOD = 998'244'353;
int dp[MAXN + 1][MAXN + 2][(MAXN)*(MAXN+1)/2 + 1];
long long FAC[MAXN+1], INV_FAC[MAXN+1];
long long binexp(long long b, int e) {
long long res = 1;
for (; e; b = b * b % MOD, e >>= 1) {
if (e&1) res = res * b % MOD;
}
return res;
}
void set_up() {
FAC[0] = 1;
for (int i = 1; i <= MAXN; i++) {
FAC[i] = FAC[i-1] * i % MOD;
}
INV_FAC[MAXN] = binexp(FAC[MAXN], MOD-2);
for (int i = MAXN-1; i >= 0; i--) {
INV_FAC[i] = INV_FAC[i+1] * (i+1) % MOD;
}
}
long long choose(int n, int k) {
if (k > n) {
return 0;
}
return (FAC[n] * INV_FAC[k] % MOD) * INV_FAC[n-k] % MOD;
}
int main() {
cin.tie(0)->sync_with_stdio(0);
cin >> n >> k >> t;
set_up();
// Base case
for (int used = 1; used <= n+1; used++) {
dp[1][used][choose(used, 2)] = 1;
}
// Do dp
for (int pused = 1; pused < k; pused++) {
for (int used = 1; used <= n+1; used++) {
for (int goodness = 0; goodness <= t; goodness++) {
// Don't use prefix value
add(dp[pused + 1][used][goodness], dp[pused][used][goodness])
// Use prefix value
for (int new_used = 1;
new_used + used <= n+1 and
goodness + choose(new_used, 2) <= t;
new_used++) {
add(dp[pused + 1][used + new_used][goodness + choose(new_used, 2)],
dp[pused][used][goodness] * choose(used-1 + new_used, new_used) % MOD)
}
}
}
}
cout << dp[k][n+1][t];
}
詳細信息
Test #1:
score: 100
Accepted
time: 0ms
memory: 3492kb
input:
2 5 1
output:
12
result:
ok 1 number(s): "12"
Test #2:
score: 0
Accepted
time: 2ms
memory: 3716kb
input:
7 10 15
output:
2016
result:
ok 1 number(s): "2016"
Test #3:
score: 0
Accepted
time: 35ms
memory: 15784kb
input:
46 50 171
output:
645560469
result:
ok 1 number(s): "645560469"
Test #4:
score: -100
Wrong Answer
time: 8ms
memory: 19988kb
input:
64 64 0
output:
1
result:
wrong answer 1st numbers differ - expected: '0', found: '1'