oj.uz

Submission #726447

# Submission time Handle Problem Language Result Execution time Memory
726447 2023-04-18T23:29:25 Z Tigerpants Portals (BOI14_portals) C++17
70 / 100
 1000 ms 90724 KB 
#include <iostream>
#include <vector>
#include <algorithm>
#include <set>
#include <map>
#include <numeric>
#include <functional>
#include <queue>

using namespace std;

typedef long long int ll;
typedef vector<ll> vll;
typedef vector<vll> vvll;
typedef vector<bool> vb;
typedef vector<vb> vvb;
typedef pair<ll, ll> pll;
typedef vector<pll> vpll;


#define rep(i, a, b) for (ll i = a; i < b; i++)
#define mp(a, b) make_pair(a, b)
#define sz(a) a.size()
#define pb(a) push_back(a)

const ll INF = 1000000000;

vvll wall;
vvll dp;
vvll portal[4]; // for each of the 4 directions, get the distance to the wall...

pll start;
pll cake;
ll R, C;
vvb board;

ll dx[4] = {1, 0, -1, 0};
ll dy[4] = {0, 1, 0, -1};

void calc_wall();
void calc_goal();
void calc_portal();

bool dp_compare(pll a, pll b) {
    if (dp[a.first][a.second] == dp[b.first][b.second]) {
        return a < b;
    }
    return dp[a.first][a.second] < dp[b.first][b.second];
}
set<pll, decltype(dp_compare)*> BFS(dp_compare);

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    cin >> R >> C;
    board.resize(R + 2);
    char tmp;
    board[0].resize(C + 2);
    board[R + 1].resize(C + 2);
    rep(j, 0, C + 2) {board[0][j] = false; board[R + 1][j] = false;}
    rep(i, 1, R + 1) {
        board[i].resize(C + 2);
        board[i][0] = false;
        board[i][C + 1] = false;
        rep(j, 1, C + 1) {
            cin >> tmp;
            board[i][j] = (tmp != '#');
            if (tmp == 'S') {
                start = mp(i, j);
            }
            if (tmp == 'C') {
                cake = mp(i, j);
            }
        }
    }
    R += 2;
    C += 2;

    wall.resize(R);
    dp.resize(R);
    rep(i, 0, 4) portal[i].resize(R);

    rep(i, 0, R) {
        wall[i].resize(C);
        dp[i].resize(C);
        rep(j, 0, 4) portal[j][i].resize(C);
        rep(j, 0, C) dp[i][j] = INF;
    }

    // calculate supporting values
    calc_wall();
    calc_portal();

    // do BFS in dp graph...
    dp[start.first][start.second] = 0;

    rep(i, 0, R) {
        rep(j, 0, C) {
            if (board[i][j]) BFS.insert(mp(i, j));
        }
    }

    while (!BFS.empty()) {
        pll pos = *BFS.begin();
        BFS.erase(BFS.begin());
        
        rep(k, 0, 4) {
            // try walking
            pll next = mp(pos.first + dx[k], pos.second + dy[k]);
            if (BFS.find(next) != BFS.end()) {
                if (dp[next.first][next.second] > dp[pos.first][pos.second] + 1) {
                    BFS.erase(next);
                    dp[next.first][next.second] = dp[pos.first][pos.second] + 1;
                    BFS.insert(next);
                }
            }

            // try shooting
            if (portal[k][pos.first][pos.second] < 1) continue;
            next = mp(pos.first + (dx[k] * portal[k][pos.first][pos.second]), pos.second + (dy[k] * portal[k][pos.first][pos.second]));
            if (BFS.find(next) != BFS.end()) {
                if (dp[next.first][next.second] > dp[pos.first][pos.second] + wall[pos.first][pos.second]) {
                    BFS.erase(next);
                    dp[next.first][next.second] = dp[pos.first][pos.second] + wall[pos.first][pos.second];
                    BFS.insert(next);
                }
            }
        }
    }

    cout << dp[cake.first][cake.second] << endl;

    return 0;
}

void calc_wall() {
    vvb vis(R, vb(C, false));
    vpll p, q;
    rep(i, 0, R) {
        rep(j, 0, C) {
            if (!board[i][j]) {
                q.pb(mp(i, j));
                wall[i][j] = 0;
                vis[i][j] = true;
            }
        }
    }
    while (!q.empty()) {
        for (vpll::iterator itr = q.begin(); itr != q.end(); itr++) {
            rep(d, 0, 4) {
                pll next = mp(itr->first + dx[d], itr->second + dy[d]);
                if ((next.first == -1) || (next.second == -1) || (next.first == R) || (next.second == C)) continue;
                if (!vis[next.first][next.second]) {
                    vis[next.first][next.second] = true;
                    wall[next.first][next.second] = wall[itr->first][itr->second] + 1;
                    p.pb(next);
                }
            }
        }
        swap(p, q);
        p.clear();
    }
}

ll portal_dp(ll i, ll j, ll k) {
    if (portal[k][i][j] == -2) portal[k][i][j] = portal_dp(i + dx[k], j + dy[k], k) + 1;
    return portal[k][i][j];
}

void calc_portal() {
    // setup before call dp
    rep(i, 0, R) {
        rep(j, 0, C) {
            rep(k, 0, 4) {
                portal[k][i][j] = -1 -(board[i][j]);
            }
        }
    }

    rep(i, 0, R) {
        rep(j, 0, C) {
            rep(k, 0, 4) {
                portal_dp(i, j, k);
            }
        }
    }
}

// There is a (RC)^3 dp
// There is also a (RC)^2 dp: if there are 2 portals then one should b-line to one of them

// For each cell we define the following distances:
// Distance to cell before nearest wall
// Distance to goal
// Then from each cell we can do one of 3 operations:
// Move a step up/down/left/right
// Shoot a portal to a wall up/down/left/right and go to nearest wall to appear at where we shot
// Move to goal
// This gives us a 9*RC dp with RC statest and 9 edges per state...

Subtask #1
11.0 / 11.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 212 KB Output is correct
2 Correct 0 ms 212 KB Output is correct
3 Correct 1 ms 212 KB Output is correct
4 Correct 0 ms 212 KB Output is correct
5 Correct 0 ms 212 KB Output is correct
6 Correct 1 ms 212 KB Output is correct
7 Correct 1 ms 212 KB Output is correct
8 Correct 1 ms 212 KB Output is correct
9 Correct 1 ms 212 KB Output is correct
10 Correct 0 ms 212 KB Output is correct

Subtask #2
20.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 212 KB Output is correct
2 Correct 0 ms 212 KB Output is correct
3 Correct 1 ms 212 KB Output is correct
4 Correct 0 ms 212 KB Output is correct
5 Correct 1 ms 212 KB Output is correct
6 Correct 1 ms 212 KB Output is correct
7 Correct 1 ms 212 KB Output is correct
8 Correct 0 ms 212 KB Output is correct
9 Correct 4 ms 596 KB Output is correct
10 Correct 4 ms 596 KB Output is correct
11 Correct 2 ms 468 KB Output is correct
12 Correct 3 ms 468 KB Output is correct
13 Correct 3 ms 468 KB Output is correct
14 Correct 0 ms 212 KB Output is correct
15 Correct 3 ms 488 KB Output is correct
16 Correct 0 ms 212 KB Output is correct

Subtask #3
20.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 212 KB Output is correct
2 Correct 1 ms 212 KB Output is correct
3 Correct 0 ms 212 KB Output is correct
4 Correct 1 ms 212 KB Output is correct
5 Correct 41 ms 3680 KB Output is correct
6 Correct 44 ms 3732 KB Output is correct
7 Correct 47 ms 3900 KB Output is correct
8 Correct 35 ms 3916 KB Output is correct

Subtask #4
19.0 / 19.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 212 KB Output is correct
2 Correct 1 ms 212 KB Output is correct
3 Correct 1 ms 212 KB Output is correct
4 Correct 0 ms 212 KB Output is correct
5 Correct 1 ms 212 KB Output is correct
6 Correct 1 ms 212 KB Output is correct
7 Correct 1 ms 212 KB Output is correct
8 Correct 1 ms 212 KB Output is correct
9 Correct 4 ms 596 KB Output is correct
10 Correct 4 ms 596 KB Output is correct
11 Correct 2 ms 468 KB Output is correct
12 Correct 3 ms 468 KB Output is correct
13 Correct 3 ms 468 KB Output is correct
14 Correct 44 ms 3744 KB Output is correct
15 Correct 40 ms 3760 KB Output is correct
16 Correct 52 ms 3860 KB Output is correct
17 Correct 43 ms 3828 KB Output is correct
18 Correct 56 ms 4208 KB Output is correct
19 Correct 65 ms 4784 KB Output is correct
20 Correct 66 ms 4776 KB Output is correct
21 Correct 35 ms 3676 KB Output is correct
22 Correct 36 ms 3796 KB Output is correct
23 Correct 39 ms 3800 KB Output is correct
24 Correct 79 ms 4768 KB Output is correct
25 Correct 1 ms 212 KB Output is correct
26 Correct 3 ms 468 KB Output is correct
27 Correct 0 ms 212 KB Output is correct
28 Correct 35 ms 3916 KB Output is correct

Subtask #5
0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 212 KB Output is correct
2 Correct 1 ms 212 KB Output is correct
3 Correct 0 ms 212 KB Output is correct
4 Correct 0 ms 212 KB Output is correct
5 Correct 0 ms 212 KB Output is correct
6 Correct 0 ms 212 KB Output is correct
7 Correct 1 ms 212 KB Output is correct
8 Correct 1 ms 212 KB Output is correct
9 Correct 4 ms 512 KB Output is correct
10 Correct 4 ms 596 KB Output is correct
11 Correct 2 ms 468 KB Output is correct
12 Correct 2 ms 468 KB Output is correct
13 Correct 3 ms 468 KB Output is correct
14 Correct 35 ms 3756 KB Output is correct
15 Correct 42 ms 3720 KB Output is correct
16 Correct 44 ms 3892 KB Output is correct
17 Correct 43 ms 3892 KB Output is correct
18 Correct 63 ms 4232 KB Output is correct
19 Correct 94 ms 4796 KB Output is correct
20 Correct 66 ms 4692 KB Output is correct
21 Correct 39 ms 3664 KB Output is correct
22 Correct 39 ms 3784 KB Output is correct
23 Correct 42 ms 3840 KB Output is correct
24 Execution timed out 1089 ms 90724 KB Time limit exceeded
25 Halted 0 ms 0 KB -