QOJ.ac
QOJ
ID | Problem | Submitter | Result | Time | Memory | Language | File size | Submit time | Judge time |
---|---|---|---|---|---|---|---|---|---|
#55726 | #1970. Social Distancing | Sa3tElSefr# | AC ✓ | 24ms | 13308kb | C++ | 2.9kb | 2022-10-14 23:10:25 | 2022-10-14 23:10:26 |
Judging History
answer
#include <bits/stdc++.h>
#define ll long long
#define ld double
using namespace std;
const int N = 500 + 5, mod = 998244353;
int n, m, dis[N][N], id, vis[N][N], vis2[N][N];
int fromR, fromC, toR, toC;
vector<pair<int, int> > src;
char a[N][N];
int dr[] = {0, 0, 1, -1};
int dc[] = {1, -1, 0, 0};
bool valid(int r, int c) {
return r >= 0 && r < n && c >= 0 && c < m;
}
void bfs() {
queue<pair< pair<int, int>, pair<int, int> > > q;
for(auto i: src) {
q.push({i, {0, 0}});
dis[i.first][i.second] = 0;
}
while((int) q.size() > 0) {
int r = q.front().first.first, c = q.front().first.second;
int kamR = q.front().second.first, kamC = q.front().second.second;
q.pop();
for(int i = 0; i < 4; i++) {
int nr = r + dr[i], nc = c + dc[i];
int nkamR = kamR + dr[i], nkamC = kamC + dc[i];
if(valid(nr, nc) && dis[nr][nc] > max(abs(nkamR), abs(nkamC))) {
dis[nr][nc] = max(abs(nkamR), abs(nkamC));
q.push({{nr, nc}, {nkamR, nkamC}});
}
}
}
}
void dfs(int r, int c) {
vis[r][c] = 1;
for(int i = 0; i < 4; i++) {
int nr = r + dr[i], nc = c + dc[i];
if(valid(nr, nc) && a[nr][nc] != '#' && a[nr][nc] != '*' && vis[nr][nc] == 0) {
dfs(nr, nc);
}
}
}
void dfs2(int r, int c, int d) {
if(dis[r][c] < d) {
return;
}
vis2[r][c] = id;
for(int i = 0; i < 4; i++) {
int nr = r + dr[i], nc = c + dc[i];
if(valid(nr, nc) && a[nr][nc] != '#' && vis2[nr][nc] != id) {
dfs2(nr, nc, d);
}
}
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
cin >> n >> m;
for(int i = 0; i < n; i++) {
for(int j = 0; j < m; j++) {
cin >> a[i][j];
dis[i][j] = mod;
if(a[i][j] == 'S') {
fromR = i;
fromC = j;
}
else if(a[i][j] == 'E') {
toR = i;
toC = j;
}
else if(a[i][j] == '*') {
src.push_back({i, j});
}
}
}
bfs();
// for(int i = 0; i < n; i++) {
// for(int j = 0; j < m; j++) {
// cout << dis[i][j] << ' ';
// }
// cout << '\n';
// }
dfs(fromR, fromC);
if(vis[toR][toC] == 0) {
cout << -1;
return 0;
}
if((int) src.size() == 0) {
cout << "safe";
return 0;
}
int low = 1, high = 1200, ans = 1500;
while(high >= low) {
id++;
int mid = low + high >> 1;
dfs2(fromR, fromC, mid);
if(vis2[toR][toC] == id) {
ans = mid;
low = mid + 1;
}
else high = mid - 1;
}
cout << ans << '\n';
return 0;
}
Details
Tip: Click on the bar to expand more detailed information
Test #1:
score: 100
Accepted
time: 2ms
memory: 3592kb
input:
4 5 .*#.. .*..E ..##. S....
output:
2
result:
ok single line: '2'
Test #2:
score: 0
Accepted
time: 1ms
memory: 3772kb
input:
6 8 .......E ........ ........ .....**. ........ S.......
output:
3
result:
ok single line: '3'
Test #3:
score: 0
Accepted
time: 2ms
memory: 3640kb
input:
3 3 #E# ### #S#
output:
-1
result:
ok single line: '-1'
Test #4:
score: 0
Accepted
time: 2ms
memory: 3564kb
input:
3 3 .S. *** .E.
output:
-1
result:
ok single line: '-1'
Test #5:
score: 0
Accepted
time: 2ms
memory: 3584kb
input:
3 3 S.. ... ..E
output:
safe
result:
ok single line: 'safe'
Test #6:
score: 0
Accepted
time: 2ms
memory: 3700kb
input:
2 2 S. .E
output:
safe
result:
ok single line: 'safe'
Test #7:
score: 0
Accepted
time: 2ms
memory: 4040kb
input:
50 50 .............##.........*....#...##....#.......... .##..........#...#............##.....#....#.....#. .........##...#....#.......#......#............... #..##..#.........*...#..........*..............#.. ....................*..#.....#.......#........#... ...#...............#................##....
output:
3
result:
ok single line: '3'
Test #8:
score: 0
Accepted
time: 17ms
memory: 9168kb
input:
495 496 S......................................................................................................................................................................................................................................................................................................
output:
13
result:
ok single line: '13'
Test #9:
score: 0
Accepted
time: 12ms
memory: 6580kb
input:
500 500 #.*#.##.**.#...#.*.*#.#.*.*#.#.*.##*.#.*..#..*...*##.#.##.#...**#*#.#*...#.#.......#*#...#...*#.#.*#.##..##...*.#.##.*#*..#...*##..##**...*#..##...##...#....*#..##*##....#.#**.#...##..#.##..#*.*#.*.....*#...##...###.##..#**....#####..*..#...#...*.....##*#*##.#..#*.*.*.*.#..*.#*#*#**.......#....
output:
-1
result:
ok single line: '-1'
Test #10:
score: 0
Accepted
time: 16ms
memory: 11108kb
input:
500 500 ....................................................................................................................................................................................S..................................................................................................................
output:
-1
result:
ok single line: '-1'
Test #11:
score: 0
Accepted
time: 24ms
memory: 11260kb
input:
500 500 *......................................................................................................................................................................................................................................................................................................
output:
8
result:
ok single line: '8'
Test #12:
score: 0
Accepted
time: 3ms
memory: 10244kb
input:
500 500 S###################################################################################################################################################################################################################################################################################################...
output:
safe
result:
ok single line: 'safe'
Test #13:
score: 0
Accepted
time: 20ms
memory: 13308kb
input:
499 499 .#.....#...#.....#.............##..............#....#.#...#..#......#......#.........................#.#.....#.....#....#..#.#........#....*...#......#..........................#...#......#..............#...*........#.......#...............................................#......................
output:
5
result:
ok single line: '5'
Test #14:
score: 0
Accepted
time: 17ms
memory: 9148kb
input:
500 500 S......................................................................................................................................................................................................................................................................................................
output:
38
result:
ok single line: '38'
Test #15:
score: 0
Accepted
time: 14ms
memory: 10908kb
input:
498 493 *......................................................................................................................................................................................................................................................................................................
output:
5
result:
ok single line: '5'