Submission #333968

#	Time	Username	Problem	Language	Result	Execution time	Memory
333968		VROOM_VARUN	Nafta (COI15_nafta)	C++14	100 / 100	970 ms	157548 KiB

nafta

/*
ID: varunra2
LANG: C++
TASK: nafta
*/

#include <bits/stdc++.h>
using namespace std;

#ifdef DEBUG
#include "lib/debug.h"
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
#define debug_arr(...) \
  cerr << "[" << #__VA_ARGS__ << "]:", debug_arr(__VA_ARGS__)
#pragma GCC diagnostic ignored "-Wsign-compare"
//#pragma GCC diagnostic ignored "-Wunused-parameter"
//#pragma GCC diagnostic ignored "-Wunused-variable"
#else
#define debug(...) 42
#endif

#define EPS 1e-9
#define IN(A, B, C) assert(B <= A && A <= C)
#define INF (int)1e9
#define MEM(a, b) memset(a, (b), sizeof(a))
#define MOD 1000000007
#define MP make_pair
#define PB push_back
#define all(cont) cont.begin(), cont.end()
#define rall(cont) cont.end(), cont.begin()
#define x first
#define y second

const double PI = acos(-1.0);
typedef long long ll;
typedef long double ld;
typedef pair<int, int> PII;
typedef map<int, int> MPII;
typedef multiset<int> MSETI;
typedef set<int> SETI;
typedef set<string> SETS;
typedef vector<int> VI;
typedef vector<PII> VII;
typedef vector<VI> VVI;
typedef vector<string> VS;

#define rep(i, a, b) for (int i = a; i < (b); ++i)
#define trav(a, x) for (auto& a : x)
#define sz(x) (int)(x).size()
typedef pair<int, int> pii;
typedef vector<int> vi;
#pragma GCC diagnostic ignored "-Wsign-compare"
// util functions

int n, m;

int hsh(int u, int v) { return u * m + v; }

int hsh(PII u) { return u.x * m + u.y; }

PII unhsh(int u) { return MP(u / m, u % m); }

int xunhsh(int u) { return u % m; }

struct dsu {
  int n;
  VI par;
  VI siz;
  VI cost;

  void init(int _n) {
    n = _n;
    siz.assign(n, 1);
    par.resize(n);
    cost.resize(n, 0);
    iota(all(par), 0);
  }

  void set(int ind, int val) { cost[ind] = val; }

  int find(int x) {
    while (par[x] != par[par[x]]) par[x] = par[par[x]];
    return par[x];
  }

  bool same(int x, int y) { return find(x) == find(y); }

  void merge(int x, int y) {
    if (same(x, y)) return;
    x = find(x);
    y = find(y);
    if (siz[x] < siz[y]) swap(x, y);
    par[y] = x;
    siz[x] += siz[y];
    cost[x] += cost[y];
  }

  int gcost(int x) { return cost[find(x)]; }
} dsu1;

VVI grid;
VVI cost;
VI sum;
vector<vector<bool>> vis;
int gp = 0;
VVI group;
VI sums;
VI start;

VI dx = {0, -1, 0, 1};
VI dy = {1, 0, -1, 0};

bool inbnds(int i, int j) { return i >= 0 and i < n and j >= 0 and j < m; }

int mn;

void dfs(int nx, int ny) {
  if (!inbnds(nx, ny)) return;
  if (grid[nx][ny] == -1) return;
  if (vis[nx][ny]) return;
  vis[nx][ny] = true;
  group[nx][ny] = gp;
  mn = min(mn, ny);
  sums.back() += grid[nx][ny];
  for (int dir = 0; dir < 4; dir++) {
    dfs(nx + dx[dir], ny + dy[dir]);
  }
}

void calc(int ind) {
  VI use;
  for (int i = 0; i < n; i++) {
    if (vis[i][ind]) use.PB(group[i][ind]);
  }
  sort(all(use));
  use.resize(unique(all(use)) - use.begin());
  int sum = 0;
  VVI events;
  trav(x, use) sum += sums[x], events.PB({start[x], 0, -sums[x]});
  for (int i = 0; i < ind; i++) {
    events.PB({i, 1});
  }
  cost[ind + 1][0] = sum;
  sort(all(events));

  trav(x, events) {
    if (x[1] == 0) {
      sum += x[2];
    } else
      cost[ind + 1][x[0] + 1] = sum;
  }
}
vector<long long> dp_before, dp_cur;

void init() {
  grid.resize(n);
  trav(x, grid) x.resize(m);
  cost.resize(m + 1);
  trav(x, cost) x.assign(m + 1, 0);
  dp_before.assign(m + 1, 0);
  dp_cur.assign(m + 1, 0);
  group.resize(n);
  trav(x, group) x.resize(m);
  vis.resize(n);
  trav(x, vis) x.assign(m, false);
}

long long C(int i, int j) { return cost[j][i]; }

// compute dp_cur[l], ... dp_cur[r] (inclusive)
void compute(int l, int r, int optl, int optr) {
  if (l > r) return;
  int mid = (l + r) >> 1;
  pair<int, int> best = {-1, -1};

  for (int k = optl; k <= min(mid, optr); k++) {
    best = max(best, {dp_before[k] + C(k, mid), k});
  }

  dp_cur[mid] = best.first;
  int opt = best.second;

  compute(l, mid - 1, optl, opt);
  compute(mid + 1, r, opt, optr);
}

void compute1() {
  for (int i = 0; i <= m; i++) {
    for (int j = 0; j <= i; j++) {
      dp_cur[i] = max(dp_cur[i], dp_before[j] + C(j, i));
    }
  }
}

int main() {
  cin.sync_with_stdio(0);
  cin.tie(0);

  cin >> n >> m;
  init();
  dsu1.init(n * m);

  rep(i, 0, n) rep(j, 0, m) {
    char c;
    cin >> c;
    if (c == '.')
      grid[i][j] = -1;
    else
      grid[i][j] = c - '0';
    // dsu1.set(hsh(i, j), grid[i][j]);
  }

  for (int i = 0; i < n; i++) {
    for (int j = 0; j < m; j++) {
      if (vis[i][j]) continue;
      if (grid[i][j] == -1) continue;
      mn = INF;
      sums.PB(0);
      dfs(i, j);
      gp++;
      start.PB(mn);
    }
  }

  for (int i = 0; i < m; i++) {
    calc(i);
  }

  for (int i = 0; i < m; i++) {
    compute(0, m, 0, m);
    cout << *max_element(all(dp_cur)) << '\n';
    swap(dp_cur, dp_before);
  }

  return 0;
}

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