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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 |
---|---|---|---|---|---|---|---|---|---|
#106252 | #4231. Rafting Trip | zaxwellmen# | RE | 2ms | 3324kb | C++20 | 2.9kb | 2023-05-17 02:35:35 | 2023-05-17 02:35:39 |
Judging History
answer
#include<bits/stdc++.h>
using namespace std;
typedef pair<int, int> pi;
#define FOR(i, a, b) for (int i = (a); i < (b); i++)
#define F0R(i, a) FOR(i, 0, a)
#define mp make_pair
// right down left up
int dx[4] = {0, 1, 0, -1}, dy[4] = {1, 0, -1, 0};
map<char, int> dir = {{'>', 0}, {'v', 1}, {'<', 2}, {'^', 3}};
int n, m, ans;
vector<string> grid;
vector<vector<bool>> vis, iscycle;
vector<vector<pi>> tail;
map<pi, int> cnt;
bool river(int i, int j) {
return i >= 0 && i < n && j >= 0 && j < m && dir.find(grid[i][j]) != dir.end();
}
bool landmark(int i, int j) {
return i >= 0 && i < n && j >= 0 && j < m && grid[i][j]=='#';
}
void check(int i, int j) {
if (tail[i][j] != mp(-1, -1)) return;
if (vis[i][j]) {
tail[i][j] = mp(i, j);
iscycle[i][j] = true;
int x = i, y = j;
do {
int d = dir[grid[x][y]];
x += dx[d], y += dy[d];
iscycle[x][y] = true;
} while (mp(x,y) != mp(i,j));
return;
}
vis[i][j] = true;
int d = dir[grid[i][j]], ni = i+dx[d], nj = j+dy[d];
if (! river(ni, nj)) {
tail[i][j] = mp(i,j);
vis[i][j] = false;
return;
}
check(ni, nj);
tail[i][j] = tail[ni][nj];
vis[i][j] = false;
return;
}
void dfs(int i, int j) {
if (vis[i][j]) return;
vis[i][j] = true;
F0R(d, 4) if (landmark(i+dx[d], j+dy[d])) cnt[mp(i+dx[d], j+dy[d])]++;
ans = max(ans, (int)cnt.size());
F0R(d, 4) {
int ni = i+dx[d], nj = j+dy[d];
if (river(ni, nj) && dir[grid[ni][nj]] == (d+2)%4) dfs(ni, nj);
}
F0R(d, 4) if (landmark(i+dx[d], j+dy[d])) {
pi p = mp(i+dx[d], j+dy[d]);
if (cnt[p]==1) cnt.erase(p);
else cnt[p]--;
}
vis[i][j] = false;
}
int main() {
ios_base::sync_with_stdio(0); cin.tie(0);
cin >> n >> m;
grid.resize(n);
F0R(i, n) cin >> grid[i];
vis.assign(n, vector<bool>(m, false));
iscycle = vis;
tail.assign(n, vector<pi>(m, mp(-1, -1)));
F0R(i, n) F0R(j, m) {
if (river(i,j)) {
int d = dir[grid[i][j]];
if (! river(i + dx[d], j + dy[d])) {
dfs(i, j);
} else check(i, j);
}
}
F0R(i, n) F0R(j, m) if (iscycle[i][j]) {
int x = i, y = j;
vector<pi> starts;
do {
iscycle[x][y] = false;
F0R(d, 4) {
int nx = x+dx[d], ny = y+dy[d];
if (landmark(nx, ny)) cnt[mp(nx, ny)]++;
if (river(nx, ny) && dir[grid[nx][ny]] == (d+2)%4) starts.push_back(mp(nx, ny));
}
int d = grid[x][y];
x += dx[d]; y += dy[d];
} while (mp(x,y) != mp(i,j));
ans = max(ans, (int)cnt.size());
for (pi p : starts) dfs(p.first, p.second);
cnt.clear();
}
cout << ans << '\n';
return 0;
}
詳細信息
Test #1:
score: 100
Accepted
time: 2ms
memory: 3324kb
input:
5 6 v<<<#v v#v<.> >>v<<< ..v##^ #<<<.^
output:
4
result:
ok single line: '4'
Test #2:
score: -100
Runtime Error
input:
4 5 >v<<. ^<..# #...# .#>^#