QOJ.ac
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 |
---|---|---|---|---|---|---|---|---|---|
#541623 | #1995. Sprinklers 2: Return of the Alfalfa | Dimash | 0 | 0ms | 0kb | C++17 | 2.6kb | 2024-08-31 20:13:56 | 2024-08-31 20:13:57 |
answer
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N = 2e3 + 12, MOD = (int)1e9 + 7;
ll binpow(ll a, ll b) {
ll ret = 1,k = a;
while(b) {
if(b & 1) {
ret *= k;
ret %= MOD;
}
k *= k;
k %= MOD;
b >>= 1;
}
return ret;
}
int n, a[N][N], s[N][N], st[N * N], col = 0, dp[N][N], pref[N][N];
int res = 0;
void add(int &a, int b) {
a += b;
if(a >= MOD) a -= MOD;
}
void test() {
cin >> n;
st[0] = 1;
for(int i = 1; i <= n * n; i++) {
st[i] = (st[i - 1] + st[i - 1]) % MOD;
}
int div2 = binpow(2, MOD - 2);
for(int i = 1; i <= n; i++) {
for(int j = 1; j <= n; j++) {
char x;
cin >> x;
a[i][j] = (x == '.');
col += a[i][j];
}
}
dp[0][0] = st[col];
for(int i = 1; i <= n; i++) {
pref[0][i] = st[col];
if(i == 1 || a[1][i - 1]) {
s[0][i] = pref[0][i];
}
}
for(int i = 1; i <= n; i++) {
for(int j = 1; j <= n; j++) {
// for(int i1 = i - 1; i1 >= 0; i1--) {
// if(j == 1 || a[i1 + 1][j - 1]) {
// for(int j1 = j - 1; j1 >= 0; j1--) {
// int _ = div2;
// if(j != 1) {
// _ = (_ *1ll* div2)%MOD;
// }
// add(dp[i][j], dp[i1][j1] * 1ll * _ % MOD);
// }
// }
// }
s[i][j] = s[i - 1][j];
pref[i][j] = pref[i][j - 1];
if(a[i][j]) {
int _ = div2;
if(j != 1) {
_ = (_ *1ll* div2)%MOD;
}
add(dp[i][j],s[i - 1][j] * 1ll * _ % MOD);
}
if(j == 1 || a[i + 1][j - 1]) {
add(s[i][j], pref[i][j - 1]);
}
add(pref[i][j],dp[i][j]);
int cf = 1;
if(i == n || a[i + 1][n]) {
if(i != n) {
cf = div2;
}
add(res,dp[i][j] * 1ll * cf % MOD);
}
}
}
if(a[1][n]) {
add(res, st[col - 1]);
}
cout << res << '\n';
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(0);
freopen("sprinklers2.in","r",stdin);
freopen("sprinklers2.out","w",stdout);
int t = 1;
// cin >> t;
while(t--)
test();
return 0;
}
詳細信息
Pretests
Final Tests
Test #1:
score: 0
Dangerous Syscalls
input:
2 .. ..
output:
result:
Test #2:
score: 0
Dangerous Syscalls
input:
4 ..W. ..WW WW.. ...W
output:
result:
Test #3:
score: 0
Dangerous Syscalls
input:
7 .WWWW.. W.WWWWW W.WW.W. WWWWWWW WWW.WWW WWWWWWW WW.WWW.
output:
result:
Test #4:
score: 0
Dangerous Syscalls
input:
10 WWW..WWWWW WWWWWWWWWW WWWWWWWWWW WWWW.WWWWW WWWWWWWW.. WWWWWWWWWW WWWWWWWWWW WWWW.WWW.W WWWWWWWWW. W.WWWW.WWW
output:
result:
Test #5:
score: 0
Dangerous Syscalls
input:
200 ..W...W.W..WWW....W...W..W........W..W.W...W.WW.WWW.WWW..W....WW.WW.........W..WW.WW..WW....WW...W..W.W.WW.WWW.W...W....W.WW.........W.W.WW.WWW...........W...W..W.....W..W.......W..WW.WW......W...WWW. W..WWWW.W......W.....W......WW.W.W....W.WW.W........WW...W...WW.W.W...W...W...WW.W.WW....W..WW....
output:
result:
Test #6:
score: 0
Dangerous Syscalls
input:
200 ..W....W.W.W..W..W.W..WWW.WW...W...W...W.W.W.....WW....W..W..W..WW....W.....WWW..W.......WW.W..WW..W.WW.....W.W.W.W..W.WW..WW..W...W....WW...W.W...W.W.W....W............WW.W..W......W.W.......W.W..... W.....W...............W..W.....WWWWWWW.WW....W....WW.W...W...W....W.WW.WW..W.....W.WWWW..W.W......
output:
result:
Test #7:
score: 0
Dangerous Syscalls
input:
200 .W.......W.........W.W.W.W..W.....W..WW.W.W.WWW...W..W..W...W..W.W.W..W..W..W.....W..W....W.W....WWW.W..W.WW..WW.....W.........W......WWW....W.WW..........WWW.W.W..........W..W..WWW.W...WW.....WW..... ..W.W.....W..W...WW....WWWW....WW......W.WWW.WW.W.......W....WW.WW.......W.W.W...WWWW......W..W...
output:
result:
Test #8:
score: 0
Dangerous Syscalls
input:
200 W.WWW.....W...WWWW...WW..W.......WW...W.W.....W..W..W........WWWW.W.WW.W...WW.WW..WW......WW...WWW.......W...WW....W..W.....W.W..WWW.W.W..W......W...W...W.W..W.WW.W...W...W.W...W..W.WW.W..W...W..W.W.W WW.....W.W..W.W......W.W..WW...W...W..........W...W..W.W.W...W.W....WW.W.W.WW...WW.W..W...WWW.....
output:
result:
Test #9:
score: 0
Dangerous Syscalls
input:
200 ..W.W..W.W.WW.WW.W.W...WW...W..W...W.WW.W.W......W....W.W.WW...WW.WW.WWW.W...W.......W.W.W..WW.WWW..W..WW......WW.W...WW...WW...WWW..W....W.WW.......W..W.W.....WWWW.W....WW...W....W..W...W....WW..W..W W......WWWW.....W..........WW..W.W.....W...W...WWW......WW.......WW...WW......W.WW.W...W...WW.W...
output:
result:
Test #10:
score: 0
Dangerous Syscalls
input:
2000 W......WWWWW.W..WW......W.....WWW.......W.W.W..WW...W.....W..W..W....WWW.W.WWWW.W..W...W....W......W..WWW.WW......WW..W..W.......W.......WW..........W..WW..W..W..WWW.WW....W......W...WW.WW......W..WW......W.WW.W.W..W...W.....W.........WW.W...W...WW.WW..WWW..WW.W.WWWW....W.WW........WW.....W.W.....
output:
result:
Test #11:
score: 0
Dangerous Syscalls
input:
2000 W.WW.....W..WW.................WWW..W....W.W.WWW...W.W........WW....W..W........W.W........W.......WW..WWW..W...WW..WW...WWWW..WWWW.W.......W....W...W...W.....W...WW...WWW...WW..W.WW..W....W.WW.........WWW.W..W...WW...WWW...WWW....W..W....WW....WW.W.........W...W...WWW..WW.............W...........
output:
result:
Test #12:
score: 0
Dangerous Syscalls
input:
2000 .W....W.WW.W....WW..W.W....W.WW.W....WW.WW.....WW..W.W.........W.W.WWWW.WWWWWWWW.W....W.W..WW...W..W..W...W...W.W.W..W...WWW...WWW.....WW...W..W..W.W...........W.W..........WW...WWW..W..W..W..W.....W.W..W....WW.W.WW.WW...W..W.W....W.WW..WWW...WW..W...W........W..W.WWW..W......W.W..WW..WW...W......
output:
result:
Test #13:
score: 0
Dangerous Syscalls
input:
2000 WW..WW..WW.WW.W...W....W...WWWW...W..W.W.W....W.W.W..W....W..W..W.W......W....WW...W..WW..W.........W.W....W..W.WW.WW......W..W.W....W..WW.WWW.WWW..WW..W.W.W.....WWW..WW..W.W...W.WW.W.W...W..........W...W..W....W...W....WW........W.W...WW..W..W...WW.WW....W.......W..WWW.W...W......WWW.WW..W..W....
output:
result:
Test #14:
score: 0
Dangerous Syscalls
input:
2000 W...W..W...W.W.WW..WW....WW...W..WWW..W...W.WW.W......WW......WWW...W........WW.WWWW..W.....W.WW..W...W...WW..W...WW.W...W..WW......W.W.....W...W....W..W....W.W.W.....WW.....W.....WW...W.W.W.WW.W..W..W......W...WWW....WW...WWW..W.....W..W...WW....W.WW.W.W.W...W.W......W.....W..WWW.WW...WW..W..W...
output:
result:
Test #15:
score: 0
Dangerous Syscalls
input:
2000 .WW.....W.W.......W...W.WWW.W..W..W.W.....W...WW.WW...W...WW..W.W.W...W.WWWW.W...W.W...WW.W.W..W...W.W.W...WWW..WW....W.W......WW.WWW....W..W.W.W.W.WW....WW....W..W...W..WW.....WWW.W...W.....W..WWWW.WW........W....W.....WWW...........WW......W.W..WW.W..WW..W.W..WW.WW.W.W.W....WW..W...WW.W..W.WW...
output:
result:
Test #16:
score: 0
Dangerous Syscalls
input:
2000 .WW..WWWWW..W...W........WWWWW..W......W..WW.........WWWW....W.W.W.W..W.......W.WW..WW..WW..W.WW....W...W.WWW..W...W.....W.WW......W......W.WW.W..WWW.WWW....W....W.WW.............W.W.W...W.W......W....W.W.........W.WW....WW.......WW....W.W.W..W.W.W....W....WW.W.W.....W.........WW...W.....W.W......