Submission #1282155

#	Time	Username	Problem	Language	Result	Execution time	Memory
1282155		wedonttalkanymore	Nafta (COI15_nafta)	C++20	34 / 100	263 ms	62388 KiB

nafta

#include <bits/stdc++.h>
/*
    Phia ben kia dai duong cung chi co
    Bo cat nang niu bien thoi
*/
using namespace std;
using ll = long long;

#define int long long
#define pii pair<ll, ll>
#define fi first
#define se second

const ll N = 2e3 + 5, inf = 1e18, mod = 1e9 + 7, block = 320, lim = 19;

int m, n;
char a[N][N];
int dx[] = {-1, 0, 1, 0};
int dy[] = {0, 1, 0, -1};
struct item {
    int L, R, sum;
};
item pre[N];
int minn = inf, maxx = 0, sum = 0;
bool vst[N][N];
int cost[N][N];
int dp[N][N];

void bfs(int stx, int sty) {
    vst[stx][sty] = 1;
    queue <pii> q;
    q.push({stx, sty});
    sum += a[stx][sty] - '0';
    minn = min(minn, sty);
	maxx = max(maxx, sty);
    while(q.size()) {
        auto [x, y] = q.front();
        q.pop();
        for (int i = 0; i < 4; i++) {
            int nx = x + dx[i], ny = y + dy[i];
            if (nx < 1 || ny < 1 || nx > m || ny > n) continue;
            if (a[nx][ny] == '.' || vst[nx][ny]) continue;
            vst[nx][ny] = 1;
            sum += a[nx][ny] - '0';
            minn = min(minn, ny);
            maxx = max(maxx, ny);
            q.push({nx, ny});
        }
    }
}

bool cmp(item a, item b) {
    return a.L < b.L;
}

struct Fenwick {
    vector <int> bit;
    int sz;
    Fenwick (int _n) {
        bit.assign(_n + 5, 0);
        sz = _n;
    }
    void update(int i, int val) {
        while(i <= sz) {
            bit[i] += val;
            i += i & -i;
        }
    }
    int get(int i) {
        if (i == 0) return 0;
        int res = 0;
        while(i > 0) {
            res += bit[i];
            i -= i & -i;
        }
        return res;
    }
    int get(int l, int r) {
    	return get(r) - get(l - 1);
	}
} fw(N);

void dnc(int k, int l, int r, int L, int R) {
	if (l > r || L > R) return;
	int mid = (l + r) / 2;
	int Left = max(0LL, L);
	int Right = min(mid - 1, R);
	int pos = Left;
	for (int j = Left; j <= Right; j++) {
		dp[k][mid] = max(dp[k][mid], dp[k - 1][j] + cost[mid][j]);
		if (dp[k][mid] == dp[k - 1][j] + cost[mid][j]) pos = j;
	}
	dnc(k, l, mid - 1, L, pos);
	dnc(k, mid + 1, r, pos, R);
}

signed main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    if (fopen(".inp", "r")) {
        freopen(".inp", "r", stdin);
        freopen(".out", "w", stdout);
    }
    cin >> m >> n;
    for (int i = 1; i <= m; i++) {
        for (int j = 1; j <= n; j++) {
            cin >> a[i][j];
        }
    }
    int tt = 0;
    for (int i = 1; i <= m; i++) {
        for (int j = 1; j <= n; j++) {
            if (a[i][j] != '.' && !vst[i][j]) {
                minn = inf, maxx = 0, sum = 0;
                bfs(i, j);
                pre[++tt] = {minn, maxx, sum}; // chuan bi cac doan l r
            }
        }
    }
    sort(pre + 1, pre + tt + 1, cmp);
//    for (int i = 1; i <= tt; i++) {
//    	cout << pre[i].L << ' ' << pre[i].R << ' ' << pre[i].sum << '\n';
//	}
    priority_queue <pii, vector <pii>, greater <pii> > q;
    int l = 1;
    for (int i = 1; i <= n; i++) {
//    	cout << i << ' ';
        while(q.size() && q.top().fi < i) {
//        	cout << "at: " << q.top().se << '\n';
            int id = q.top().se;
            int L = pre[id].L, sum = pre[id].sum;
            fw.update(L, -sum);
            q.pop();
        }
//        cout << "at: " << pre[i].L << '\n';
//        fw.update(pre[i].L, pre[i].sum);
		while(l <= tt && pre[l].L <= i) {
			fw.update(pre[l].L, pre[l].sum);
			q.push({pre[l].R, l});
			l++;
		}
        for (int j = 0; j < i; j++) {
            int val = fw.get(j + 1, i);
            cost[i][j] = val;
        }
    }
//    for (int i = 1; i <= )
//    for (int i = 1; i <= n; i++) {
//        for (int j = 0; j < i; j++) cout << i << ' ' << j << ' ' << cost[i][j] << '\n';
//        cout << '\n';
//    }
    for (int k = 1; k <= n; k++) {
//        for (int i = 1; i <= n; i++) {
//        	dp[k][i] = cost[i][0];
//            for (int j = 1; j < i; j++) {
//                dp[k][i] = max(dp[k][i], dp[k - 1][j] + cost[i][j]);
//            }
//        }
		dnc(k, 1, n, 0, n - 1);
    }
    for (int k = 1; k <= n; k++) {
        int val = *max_element(dp[k] + 1, dp[k] + n + 1);
        cout << val << '\n';
    }
    return 0;
}

Compilation message (stderr)

nafta.cpp: In function 'int main()':
nafta.cpp:101:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  101 |         freopen(".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~
nafta.cpp:102:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  102 |         freopen(".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 11 / 11
• Subtask 2: 23 / 23
• Subtask 3: 0 / 66