Submission #1231682

#	Time	Username	Problem	Language	Result	Execution time	Memory
1231682		QuocSensei	Nafta (COI15_nafta)	C++20	100 / 100	353 ms	117212 KiB

nafta

#include <bits/stdc++.h>

#define ll long long
#define el cout << '\n'
#define ii pair<ll, ll>
#define fi first
#define se second

using namespace std;

const int maxn = 2e3;
const int dx[] = {-1, 0, 1, 0};
const int dy[] = {0, 1, 0, -1};
const ll INF = 1e18;

int n, m, cost[maxn + 10][maxn + 10], dp[maxn + 10][maxn + 10], cnt = 0, max_j = -1;
char a[maxn + 10][maxn + 10];
bool vis[maxn + 10][maxn + 10];

bool in_matrix(int x, int y)
{
    return x >= 1 && x <= n && y >= 1 && y <= m;
}
void dfs(int x, int y)
{
    cnt += a[x][y] - '0';
    max_j = max(max_j, y);
    vis[x][y] = 1;

    for (int k = 0; k < 4; k++)
    {
        int nx = x + dx[k];
        int ny = y + dy[k];
        if (in_matrix(nx, ny) && !vis[nx][ny] && a[nx][ny] != '.')
            dfs(nx, ny);
    }
}
void dnc(int j, int l, int r, int optl, int optr)
{
    if (l > r) return ;

    int m = l + r >> 1;
    ii best = {-INF, -1};

    for (int z = optl; z <= min(m, optr); z++)
        best = max(best, {dp[z - 1][j - 1] + cost[z][m], z});
    dp[m][j] = best.fi;

    dnc(j, l, m - 1, optl, best.se);
    dnc(j, m + 1, r, best.se, optr);
}

int main()
{
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    if (fopen("NAFTA.INP", "r"))
    {
        freopen("NAFTA.INP", "r", stdin);
        freopen("NAFTA.OUT", "w", stdout);
    }

    cin >> n >> m;
    for (int i = 1; i <= n; i++)
        for (int j = 1; j <= m; j++)
            cin >> a[i][j];
    for (int j = 1; j <= m; j++)
        for (int i = 1; i <= n; i++)
            if (!vis[i][j] && a[i][j] != '.')
            {
                dfs(i, j);
                cost[j][max_j] += cnt;
                cost[max_j + 1][max_j] -= cnt;
                cnt = 0;
                max_j = -1;
            }
    for (int j = 1; j <= m; j++)
        for (int i = 1; i <= m; i++)
            cost[i][j] += cost[i - 1][j];
    for (int i = 1; i <= m; i++)
        for (int j = 1; j <= m; j++)
            cost[i][j] += cost[i][j - 1];
//    for (int i = 1; i <= m; i++)
//    {
//        for (int j = 1; j <= m; j++)
//            cout << cost[i][j] << ' ';
//        el;
//    }
//    el;

//    for (int j = 1; j <= m; j++)
//        for (int i = 1; i <= m; i++)
//            for (int z = 1; z <= i; z++)
//                dp[i][j] = max(dp[i][j], dp[z - 1][j - 1] + cost[z][i]);

    for (int j = 1; j <= m; j++)
        dnc(j, 1, m, 1, m);
//    for (int j = 1; j <= m; j++)
//    {
//        for (int i = 1; i <= m; i++)
//            cout << dp[i][j] << ' ';
//        el;
//    }
    for (int j = 1; j <= m; j++)
        cout << dp[m][j], el;
}

Compilation message (stderr)

nafta.cpp: In function 'int main()':
nafta.cpp:58:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   58 |         freopen("NAFTA.INP", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
nafta.cpp:59:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   59 |         freopen("NAFTA.OUT", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 11 / 11
• Subtask 2: 23 / 23
• Subtask 3: 66 / 66