Submission #1105845

#	Time	Username	Problem	Language	Result	Execution time	Memory
1105845		Zero_OP	Catfish Farm (IOI22_fish)	C++17	35 / 100	103 ms	11592 KiB

fish

#include <bits/stdc++.h>
#ifndef LOCAL
    #include <fish.h>
#endif // LOCAL

using namespace std;

#define rep(i, l, r) for(int i = (l), _r = (r); i < _r; ++i)
#define FOR(i, l, r) for(int i = (l), _r = (r); i <= _r; ++i)
#define ROF(i, r, l) for(int i = (r), _l = (l); i >= _l; --i)
#define all(v) begin(v), end(v)
#define compact(v) v.erase(unique(all(v)), end(v))
#define sz(v) (int)v.size()
#define dbg(x) "[" #x " = " << (x) << "]"

template<typename T>
bool minimize(T& a, const T& b){
    if(a > b) return a = b, true; return false;
}

template<typename T>
bool maximize(T& a, const T& b){
    if(a < b) return a = b, true; return false;
}

using ll = long long;
using ld = long double;

mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
template<typename T> T random_int(T l, T r){ return uniform_int_distribution<T>(l, r)(rng); }
template<typename T> T random_real(T l, T r){ return uniform_real_distribution<T>(l, r)(rng); }

const int MAX = 3e5 + 5;

int n, m;
struct fish{
    int x, y, w;
} fishes[MAX];

namespace subtask1{
    bool check(){
        rep(i, 0, m) if(fishes[i].x& 1) return false;
        return true;
    }

    ll solve(){
        ll sum = 0;
        rep(i, 0, m){
            if((i > 0) || (i < n - 1)){
                sum += fishes[i].w;
            }
        }
        return sum;
    }
}

namespace subtask2{
    bool check(){
        for(int i = 0; i < m; ++i){
            if(fishes[i].x > 1) return false;
        }
        return true;
    }

    ll sum[3][MAX];
    ll f[3][MAX], g[3][MAX];

    ll solve(){
        memset(f, 0, sizeof(f));
        memset(g, 0, sizeof(g));

        rep(i, 0, m){
            sum[fishes[i].x][fishes[i].y] += fishes[i].w;
        }

        rep(i, 0, 2){
            rep(j, 0, n){
                sum[i][j] += (j > 0 ? sum[i][j - 1] : 0);
            }
        }

        ll ans = max(sum[0][n - 1], sum[1][n - 1]);
        if(n > 2){
            rep(i, 0, n){
                maximize(ans, sum[1][n - 1] - sum[1][i] + sum[0][i]);
            }
        }

        return ans;
    }
}

namespace subtask3{
    bool check(){
        rep(i, 0, m){
            if(fishes[i].y > 0) return false;
        }
        return true;
    }

    ll dp[MAX], s[MAX];

    ll solve(){
        rep(i, 0, m) s[fishes[i].x] = fishes[i].w;

        dp[0] = 0;
        ll res = 0;
        rep(i, 1, n){
            dp[i] = max(dp[i - 1], s[i - 1]);
            if(i >= 2) maximize(dp[i], dp[i - 2] + s[i - 1]);
            if(i >= 3) maximize(dp[i], dp[i - 3] + s[i - 2] + s[i - 1]);
            maximize(res, dp[i] + s[i + 1]);
        }

        return res;
    }
}

namespace subtask45{
    bool check(){
        return n <= 300;
    }

    ll pref[305][305];

    ll solve(){
        rep(i, 0, m){
            pref[fishes[i].x + 1][fishes[i].y + 1] += fishes[i].w;
        }

        FOR(i, 1, n){
            FOR(j, 1, n){
                pref[i][j] += pref[i][j - 1];
            }
        }

        const ll inf = 1e18;
        vector<vector<ll>> f(n + 1, vector<ll>(n + 1, -inf));
        vector<vector<ll>> g(n + 1, vector<ll>(n + 1, -inf));

        /*

        let f[c][r] = the maximum sum of weights if we put a pier (c, r) but we don't consider the fishes (c, r') with r' >= r
            g[c][r] = the maximum sum of weights if we put a pier (c, r) but we consider the fishes (c, r') with r' >= r
        let R[i] the height of pier on column c the we put

        consider when R[i - 1] < R[i] -> it contributes to f[c][r]
        consider when R[i - 1] > R[i] -> it contributes to g[c][r]

        when calculating f[c][r] :
        - consider R[i - 2] > R[i - 1] < R[i]
        - consider R[i - 2] < R[i - 1] < R[i]

        */

        FOR(i, 0, n){
            f[1][i] = g[1][i] = 0;
        }

        FOR(c, 2, n){
            FOR(r, 0, n){
                if(r == 0){
                    maximize(f[c][r], g[c - 1][r]);
                }

                FOR(k, 0, r){
                    maximize(f[c][r], f[c - 1][k] + pref[c - 1][r] - pref[c - 1][k]);
//                    cout << dbg(c) << dbg(r) << dbg(f[c - 1][k] + pref[c - 1][r] + pref[c - 1][k]) << '\n';
                }

                if(c > 2 && r > 0){
                    FOR(k, 1, n){
                        maximize(f[c][r], max(f[c - 2][k], g[c - 2][k]) + pref[c - 1][max(r, k)]);
//                        cout << dbg(c) << dbg(r) << dbg(max(f[c - 2][r], g[c - 2][r]) + pref[c - 1][max(r, k)]) << '\n';
                    }
                }

                FOR(k, r, n){
                    maximize(g[c][r], max(f[c - 1][k], g[c - 1][k]) + pref[c][k] - pref[c][r]);
//                    cout<< dbg(c) << dbg(r) << dbg(max(f[c - 1][k], g[c - 1][k]) + pref[c][k] - pref[c][r]) << '\n';
                }
            }
        }

        ll ans = 0;
        FOR(c, 1, n){
            FOR(r, 1, n){
                maximize(ans, max(f[c][r], g[c][r]) + (c < n ? pref[c + 1][r] : 0));
            }
        }

//        FOR(i, 1, n){
//            FOR(j, 1, n){
//                cout << pref[j][n - i + 1] << " \n"[j == n];
//            }
//        }
//        cout << "F[r][c] : \n";
//        FOR(i, 1, n){
//            FOR(j, 1, n){
//                cout << f[j][n - i + 1] << " \n"[j == n];
//            }
//        }
//
//        cout << '\n' << "G[r][c] : \n";
//        FOR(i, 1, n){
//            FOR(j, 1, n){
//                cout << g[j][n - i + 1] << " \n"[j == n];
//            }
//        }
//        cerr << "subtask 4, 5 : ";

        return ans;
    }
}

ll max_weights(int N, int M, vector<int> X, vector<int> Y, vector<int> W){
    n = N;
    m = M;
    rep(i, 0, M) fishes[i] = {X[i], Y[i], W[i]};

//    if(subtask1::check()) return subtask1::solve();
//    if(subtask2::check()) return subtask2::solve();
//    if(subtask3::check()) return subtask3::solve();
    if(subtask45::check()) return subtask45::solve();

    return -1;
}

#ifdef LOCAL
int main(){
    freopen("task.inp", "r", stdin);
    freopen("task.out", "w", stdout);

    int N, M;
    cin >> N >> M;
    vector<int> X(M), Y(M), W(M);
    rep(i, 0, M){
        cin >> X[i] >> Y[i] >> W[i];
    }

    cout << max_weights(N, M, X, Y, W) << '\n';
}
#endif // LOCAL

Compilation message (stderr)

fish.cpp: In function 'bool minimize(T&, const T&)':
fish.cpp:18:5: warning: this 'if' clause does not guard... [-Wmisleading-indentation]
   18 |     if(a > b) return a = b, true; return false;
      |     ^~
fish.cpp:18:35: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'if'
   18 |     if(a > b) return a = b, true; return false;
      |                                   ^~~~~~
fish.cpp: In function 'bool maximize(T&, const T&)':
fish.cpp:23:5: warning: this 'if' clause does not guard... [-Wmisleading-indentation]
   23 |     if(a < b) return a = b, true; return false;
      |     ^~
fish.cpp:23:35: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'if'
   23 |     if(a < b) return a = b, true; return false;
      |                                   ^~~~~~

• Subtask 1: 0 / 3
• Subtask 2: 0 / 6
• Subtask 3: 0 / 9
• Subtask 4: 14 / 14
• Subtask 5: 21 / 21
• Subtask 6: 0 / 17
• Subtask 7: 0 / 14
• Subtask 8: 0 / 16