Submission #1305408

#	Time	Username	Problem	Language	Result	Execution time	Memory
1305408		nikaa123	Tracks in the Snow (BOI13_tracks)	C++20	100 / 100	622 ms	117616 KiB

tracks

#include <bits/stdc++.h>
using namespace std;
 
// #define int long long 
#define eb emplace_back
#define mp make_pair
#define pb push_back
#define pp pop_back
#define endl '\n'
#define ff first
#define ss second
#define stop exit(0)
#define sz(x) (int)x.size()
#define pause system("pause")
#define all(x) (x).begin(), (x).end()
#define deb(x) cout << #x << "-" << x << endl
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
 
typedef char chr;
typedef string str;
typedef long long ll;
typedef vector<int> vii;
typedef pair<int, int> pii;
 
const long long INF = LLONG_MAX;
const int inf = INT_MAX;
const int mod = 998244353;
const int MOD = 1000000007;
const int dx[] = {-1,0,1,0};
const int dy[] = {0,1,0,-1};
const double PI = 2 * acos(0.0);
 
const int N = 4e3+5;
 
int h,w;
string bd[N];
int cnt;
int d[N][N];

bool inbound(int x, int y) {
    return (1 <= x && x <= h && 1 <= y && y <= w);
}

inline void test_case() {
    
    cin >> h >> w;
    for (int i = 1; i <= h; i++) {
        cin >> bd[i];
        bd[i] = " " + bd[i];
        for (int j = 1; j <= w; j++) {
            d[i][j] = inf;
        }
    }
    
    deque<pii> dp;
    dp.push_front({1,1});
    d[1][1] = 1;
    while (!dp.empty()) {
        auto [x,y] = dp.front();
        dp.pop_front();
        for (int i = 0; i < 4; i++){
            int nx = x + dx[i];
            int ny = y + dy[i];
            if (!inbound(nx,ny)) continue;
            if (bd[nx][ny] == '.') continue;
            int w = (bd[x][y] != bd[nx][ny]);
            if (d[nx][ny] > d[x][y]+w) {
                d[nx][ny] = d[x][y]+w;
                if (w == 1) {
                    dp.push_back({nx,ny}); 
                } else {
                    dp.push_front({nx,ny});
                }
            }
        }
    }
    int ans = -inf;
    for (int i = 1; i <= h; i++) {
        for (int j = 1; j <= w; j++) {
            if (bd[i][j] == '.') continue;
            ans = max(ans,d[i][j]);
        }
    }
    cout << ans << endl;
    
}
 
signed main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
 
    int T = 1;
    // cin >> T;
    while (T--) test_case();
    return 0;
}

• Subtask 1: 30 / 30
• Subtask 2: 70 / 70