Submission #168879

#	Time	Username	Problem	Language	Result	Execution time	Memory
168879		thecodingwizard	Nafta (COI15_nafta)	C++11	100 / 100	606 ms	94532 KiB

nafta

//#pragma GCC optimize ("O3")
//#pragma GCC target ("sse4")

#include <bits/stdc++.h>

using namespace std;

template<class T> using min_heap = priority_queue<T, vector<T>, greater<T>>;

#define FOR(i, a, b) for (int i=a; i<(b); i++)
#define F0R(i, a) for (int i=0; i<(a); i++)
#define F0R1(i, a) for (int i=1; i<=(a); i++)
#define FORd(i, a, b) for (int i = (b)-1; i >= a; i--)
#define F0Rd(i, a) for (int i = (a)-1; i >= 0; i--)
#define trav(a, x) for (auto& a : x)
#define MIN(a, b) a = min(a, b)
#define MAX(a, b) a = max(a, b)

#define INF 1000000010
#define LL_INF 4500000000000000000LL
#define LSOne(S) (S & (-S))
#define EPS 1e-9
#define pA first
#define pB second
#define mp make_pair
#define mt make_tuple
#define pb push_back
#define eb emplace_back
#define PI acos(-1.0)
// #define MOD (int)(2e+9+11)
#define MOD (int)(1e+9+7)
#define SET(vec, val, size) for (int i = 0; i < size; i++) vec[i] = val;
#define SET2D(arr, val, dim1, dim2) F0R(i, dim1) F0R(j, dim2) arr[i][j] = val;
#define SET3D(arr, val, dim1, dim2, dim3) F0R(i, dim1) F0R(j, dim2) F0R(k, dim3) arr[i][j][k] = val;
#define SET4D(arr, val, dim1, dim2, dim3, dim4) F0R(i, dim1) F0R(j, dim2) F0R(k, dim3) F0R(l, dim4) arr[i][j][k][l] = val;

#define lb lower_bound
#define ub upper_bound
#define sz(x) (int)x.size()
#define beg(x) x.begin()
#define en(x) x.end()
#define all(x) beg(x), en(x)
#define resz resize
#define SORT(vec) sort(all(vec))
#define RSORT(vec) sort(vec.rbegin(),vec.rend())

typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;
typedef pair<int, int> ii;
typedef pair<int, ii> iii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;
typedef vector<ii> vii;
typedef vector<iii> viii;
typedef vector<ll> vl;

// @formatter:off
// Source: Benq (https://github.com/bqi343/USACO) [Modified]
namespace input {
    template<class T> void re(complex<T>& x);
    template<class T1, class T2> void re(pair<T1,T2>& p);
    template<class T> void re(vector<T>& a);
    template<class T, size_t SZ> void re(array<T,SZ>& a);
    template<class T> void reA(T A[], int sz);

    template<class T> void re(T& x) { cin >> x; }
    void re(double& x) { string t; re(t); x = stod(t); }
    void re(ld& x) { string t; re(t); x = stold(t); }
    template<class Arg, class... Args> void re(Arg& first, Args&... rest) {
        re(first); re(rest...);
    }

    template<class T1, class T2> void re(pair<T1,T2>& p) { re(p.pA,p.pB); }
    template<class T> void re(vector<T>& a) { F0R(i,sz(a)) re(a[i]); }
    template<class T, size_t SZ> void re(array<T,SZ>& a) { F0R(i,SZ) re(a[i]); }
    template<class T> void reA(T A[], int sz) { F0R(i, sz) re(A[i]); }

    void setupIO(const string &PROB = "") {
        ios::sync_with_stdio(false);
        cin.tie(nullptr);
        if (PROB.length() != 0) {
            ifstream infile(PROB + ".in");
            if (infile.good()) {
                freopen((PROB + ".in").c_str(), "r", stdin);
                freopen((PROB + ".out").c_str(), "w", stdout);
            }
        }
    }
}
using namespace input;

namespace output {
    template<class T1, class T2> void prD(const pair<T1,T2>& x);
    template<class T, size_t SZ> void prD(const array<T,SZ>& x);
    template<class T> void prD(const vector<T>& x);
    template<class T> void prD(const set<T>& x);
    template<class T1, class T2> void prD(const map<T1,T2>& x);

    template<class T1, class T2> void pr(const pair<T1,T2>& x);
    template<class T, size_t SZ> void pr(const array<T,SZ>& x);
    template<class T> void pr(const vector<T>& x);
    template<class T> void pr(const set<T>& x);
    template<class T1, class T2> void pr(const map<T1,T2>& x);

    template<class T> void prD(const T& x) { cout << x; cout.flush(); }
    template<class Arg, class... Args> void prD(const Arg& first, const Args&... rest) {
        prD(first); prD(rest...);
    }

    template<class T1, class T2> void prD(const pair<T1,T2>& x) {
        prD("{",x.pA,", ",x.pB,"}");
    }
    template<class T> void prDContain(const T& x) {
        prD("{");
        bool fst = 1; for (const auto& a: x) prD(!fst?", ":"",a), fst = 0; // const needed for vector<bool>
        prD("}");
    }
    template<class T, size_t SZ> void prD(const array<T,SZ>& x) { prDContain(x); }
    template<class T> void prD(const vector<T>& x) { prDContain(x); }
    template<class T> void prD(const set<T>& x) { prDContain(x); }
    template<class T1, class T2> void prD(const map<T1,T2>& x) { prDContain(x); }

    void psD() { prD("\n"); }
    template<class Arg> void psD(const Arg& first) {
        prD(first); psD(); // no space at end of line
    }
    template<class Arg, class... Args> void psD(const Arg& first, const Args&... rest) {
        prD(first," "); psD(rest...); // print w/ spaces
    }


    template<class T> void pr(const T& x) { cout << x; }
    template<class Arg, class... Args> void pr(const Arg& first, const Args&... rest) {
        pr(first); pr(rest...);
    }

    template<class T1, class T2> void pr(const pair<T1,T2>& x) {
        pr(x.pA, " ", x.pB);
    }
    template<class T> void prContain(const T& x) {
        bool fst = 1; for (const auto& a: x) pr(!fst?" ":"",a), fst = 0; // const needed for vector<bool>
    }
    template<class T, size_t SZ> void pr(const array<T,SZ>& x) { prContain(x); }
    template<class T> void pr(const vector<T>& x) { prContain(x); }
    template<class T> void pr(const set<T>& x) { prContain(x); }
    template<class T1, class T2> void pr(const map<T1,T2>& x) { prContain(x); }

    void ps() { pr("\n"); }
    template<class Arg> void ps(const Arg& first) {
        pr(first); ps(); // no space at end of line
    }
    template<class Arg, class... Args> void ps(const Arg& first, const Args&... rest) {
        pr(first," "); ps(rest...); // print w/ spaces
    }
}
using namespace output;
// @formatter:on

/* ============================ */

#define MAXN 2100

struct FenwickTree {
public:
    vi ft;
    FenwickTree(int n) {
        ft.assign(n+1, 0);
    }
    void upd(int k, int v) {
        for (; k < sz(ft); k += LSOne(k)) ft[k] += v;
    }
    int qry(int k) {
        int sum = 0; for (; k; k -= LSOne(k)) sum += ft[k];
        return sum;
    }
};

int r, s;
char grid[2000][2000];

int leftmost, rightmost, ct;
int dx[4] = {-1,0,1,0};
int dy[4] = {0,1,0,-1};
void dfs(int i, int j) {
    MIN(leftmost, j);
    MAX(rightmost, j);
    ct += grid[i][j] - '0';
    grid[i][j] = '.';
    F0R(x, 4) {
        int a = i + dx[x], b = j + dy[x];
        if (a >= 0 && a < r && b >= 0 && b < s && grid[a][b] != '.') dfs(a, b);
    }
}

int gain[MAXN][MAXN];
int dp[MAXN][MAXN];
int dpTransition[MAXN][MAXN];

// works with condition that dpTransition[i][j] <= dpTransition[i+1][j]
void solveDP(int lo, int hi, int transitionLo, int transitionHi, int j) {
    if (lo > hi) return;
    int mid = (lo + hi)/2;
    // solve for dp[mid], dpTransition[mid]
    dp[mid][j] = -INF;
    FOR(k, max(transitionLo, mid), transitionHi+1) {
        int opt = (k==s?0:dp[k+1][j-1]) + gain[k][mid];
        if (dp[mid][j] < opt) {
            dp[mid][j] = opt;
            dpTransition[mid][j] = k;
        }
    }
    solveDP(lo, mid - 1, transitionLo, dpTransition[mid][j], j);
    solveDP(mid + 1, hi, dpTransition[mid][j], transitionHi, j);
}

int main() {
    setupIO();

    re(r, s);
    F0R(i, r) reA(grid[i], s);
    vector<pair<ii, int>> pools;
    F0R(i, r) {
        F0R(j, s) {
            if (grid[i][j] != '.') {
                leftmost = INF, rightmost = -INF, ct = 0;
                dfs(i, j);
                pools.pb({{leftmost+1, rightmost+1}, ct});
            }
        }
    }
    sort(all(pools));

    int n = s;

    // Step 1: Calculate gain
    FenwickTree FT(s+10);
    trav(pool, pools) {
        FT.upd(pool.pA.pA, pool.pB);
        FT.upd(pool.pA.pB+1, -pool.pB);
    }
    int poolIdx = 0;
    F0R(posCovered, s+1) {
        while (poolIdx < sz(pools) && pools[poolIdx].pA.pA-1 < posCovered) {
            // remove poolIdx
            auto pool = pools[poolIdx];
            FT.upd(pool.pA.pA, -pool.pB);
            FT.upd(pool.pA.pB+1, pool.pB);
            poolIdx++;
        }
        FOR(i, posCovered, s) {
            gain[i][posCovered] = FT.qry(i+1);
        }
    }

    F0R(j, s+1) {
        if (j == 0) {
            F0R(i, s+1) dp[i][j] = 0;
        } else {
            solveDP(0, s, 0, s, j);
        }
    }

    F0R1(i, s) {
        ps(dp[0][i]);
    }

    return 0;
}

Compilation message (stderr)

nafta.cpp: In function 'int main()':
nafta.cpp:234:9: warning: unused variable 'n' [-Wunused-variable]
     int n = s;
         ^
nafta.cpp: In function 'void input::setupIO(const string&)':
nafta.cpp:85:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
                 freopen((PROB + ".in").c_str(), "r", stdin);
                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
nafta.cpp:86:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
                 freopen((PROB + ".out").c_str(), "w", stdout);
                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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