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Submission #625573

# Submission time Handle Problem Language Result Execution time Memory
625573 2022-08-10T15:06:50 Z I_love_Hoang_Yen Catfish Farm (IOI22_fish) C++17
18 / 100
 94 ms 19788 KB 
#include "bits/stdc++.h"
using namespace std;

#define int long long
struct Fish {
    int col, row;
    int weight;
};
bool operator < (const Fish& a, const Fish& b) {
    if (a.col != b.col) return a.col < b.col;
    return a.row < b.row;
}

// fishes are on even columns -> build piers on odd columns
// & catch all fishes
int sub1(const std::vector<Fish>& fishes) {
    int res = 0;
    for (const auto& fish : fishes) {
        res += fish.weight;
    }
    return res;
}

// fishes are on first 2 columns
int sub2(int n, const std::vector<Fish>& fishes) {
    std::vector<int> zeroes(n);  // prefix sum of fish weights at column == 0
    std::vector<int> ones(n);    // prefix sum of fish weights at column == 1
    for (const auto& fish : fishes) {
        if (fish.col == 0) zeroes[fish.row] += fish.weight;
        if (fish.col == 1) ones[fish.row] += fish.weight;
    }

    std::partial_sum(zeroes.begin(), zeroes.end(), zeroes.begin());
    std::partial_sum(ones.begin(), ones.end(), ones.begin());

    int res = ones.back();  // init: only catch fishes at column == 1
    for (int i = 0; i < n; ++i) {
        // build pier until at column 1, row 0-i
        if (n == 2) res = std::max(res, zeroes[i]);
        else res = std::max(res, zeroes[i] + ones.back() - ones[i]);
    }
    return res;
}

// all fishes are on row == 0
int sub3(int n, const std::vector<Fish>& fishes) {
    std::vector<int> weights(n);  // weights[i] = weight of fish at column i
    for (const auto& fish : fishes) {
        weights[fish.col] += fish.weight;
    }

    // f[i] = best strategy if we BUILD PIER AT i, only considering col 0..i
    // i-4 i-3 i-2 i-1 i
    std::vector<int> f(n);
    f[0] = 0;
    for (int i = 1; i < n; ++i) {
        f[i] = std::max(f[i-1], weights[i-1]);
        if (i >= 2) {
            f[i] = std::max(f[i], f[i-2] + weights[i-1]);
        }
        if (i >= 3) {
            f[i] = std::max(f[i], f[i-3] + weights[i-2] + weights[i-1]);
        }
    }

    int res = 0;
    for (int i = 0; i < n; ++i) {
        int cur = f[i];
        if (i + 1 < n) cur += weights[i+1];
        res = std::max(res, cur);
    }
    return res;
}

int sub5(int n, const std::vector<Fish>& fishes) {
    // Init weights[i][j] = sum of fish on column i, from row 0 -> row j
    std::vector<std::vector<int>> weights(n, std::vector<int> (n, 0));
    for (const auto& fish : fishes) {
        weights[fish.col][fish.row] += fish.weight;
    }
    for (int col = 0; col < n; ++col) {
        std::partial_sum(weights[col].begin(), weights[col].end(), weights[col].begin());
    }

    // f[c][r] = best strategy if we last BUILD PIER AT column c, row r
    // only considering fishes <= (c, r)
    std::vector<std::vector<int>> f(n, std::vector<int> (n, 0)),
                                  g(n, std::vector<int> (n, 0));
    // f <= g
    for (int c = 1; c < n; ++c) {
        for (int r = 0; r < n; ++r) {
            // last pier at column i-1
            for (int lastRow = 0; lastRow < n; ++lastRow) {
                if (lastRow <= r) {
                    int cur = std::max(
                            f[c-1][lastRow] + weights[c-1][r] - weights[c-1][lastRow],
                            g[c-1][lastRow]);
                    f[c][r] = std::max(f[c][r], cur);
                    g[c][r] = std::max(g[c][r], cur);
                } else {
                    f[c][r] = std::max(f[c][r], g[c-1][lastRow]);
                    g[c][r] = std::max(
                            g[c][r],
                            g[c-1][lastRow] + weights[c][lastRow] - weights[c][r]);
                }
            }

            // last pier at column i-2
            if (c >= 2) {
                for (int lastRow = 0; lastRow < n; ++lastRow) {
                    int cur = g[c-2][lastRow] + weights[c-1][std::max(lastRow, r)];
                    f[c][r] = std::max(f[c][r], cur);
                    g[c][r] = std::max(g[c][r], cur);
                }
            }
            
            // last pier at column i-3
            if (c >= 3) {
                for (int lastRow = 0; lastRow < n; ++lastRow) {
                    int cur = g[c-3][lastRow] + weights[c-2][lastRow] + weights[c-1][r];
                    f[c][r] = std::max(f[c][r], cur);
                    g[c][r] = std::max(g[c][r], cur);
                }
            }
        }
    }

    int res = 0;
    for (int c = 0; c < n; ++c) {
        for (int r = 0; r < n; ++r) {
            assert(g[c][r] >= f[c][r]);
            int cur = g[c][r];
            if (c + 1 < n) {
                cur += weights[c+1][r];
            }
            res = std::max(res, cur);
        }
    }
    return res;
}

#undef int
long long max_weights(
        int n, int nFish,
        std::vector<int> xs,
        std::vector<int> ys,
        std::vector<int> ws) {
    std::vector<Fish> fishes;
    for (int i = 0; i < nFish; ++i) {
        fishes.push_back({xs[i], ys[i], ws[i]});
    }

    if (std::all_of(xs.begin(), xs.end(), [] (int x) { return x % 2 == 0; })) {
        return sub1(fishes);
    }
    if (*std::max_element(xs.begin(), xs.end()) <= 1) {
        return sub2(n, fishes);
    }
    if (*std::max_element(ys.begin(), ys.end()) == 0) {
        return sub3(n, fishes);
    }
    if (n <= 300) {
        return sub5(n, fishes);
    }
    return 0;
}

Subtask #1
3.0 / 3.0

# Verdict Execution time Memory Grader output
1 Correct 24 ms 5320 KB Output is correct
2 Correct 31 ms 5808 KB Output is correct
3 Correct 0 ms 212 KB Output is correct
4 Correct 0 ms 212 KB Output is correct
5 Correct 94 ms 19788 KB Output is correct
6 Correct 94 ms 19672 KB Output is correct

Subtask #2
6.0 / 6.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 212 KB Output is correct
2 Correct 50 ms 10384 KB Output is correct
3 Correct 61 ms 11212 KB Output is correct
4 Correct 25 ms 5336 KB Output is correct
5 Correct 29 ms 5952 KB Output is correct
6 Correct 1 ms 212 KB Output is correct
7 Correct 0 ms 212 KB Output is correct
8 Correct 1 ms 212 KB Output is correct
9 Correct 1 ms 212 KB Output is correct
10 Correct 0 ms 212 KB Output is correct
11 Correct 0 ms 212 KB Output is correct
12 Correct 26 ms 5464 KB Output is correct
13 Correct 29 ms 6460 KB Output is correct
14 Correct 24 ms 5444 KB Output is correct
15 Correct 28 ms 6076 KB Output is correct
16 Correct 25 ms 5472 KB Output is correct
17 Correct 27 ms 6080 KB Output is correct

Subtask #3
9.0 / 9.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 212 KB Output is correct
2 Correct 2 ms 1748 KB Output is correct
3 Correct 24 ms 4132 KB Output is correct
4 Correct 16 ms 3656 KB Output is correct
5 Correct 30 ms 6460 KB Output is correct
6 Correct 26 ms 6464 KB Output is correct
7 Correct 27 ms 6560 KB Output is correct
8 Correct 28 ms 6460 KB Output is correct

Subtask #4
0 / 14.0

# Verdict Execution time Memory Grader output
1 Incorrect 0 ms 212 KB 1st lines differ - on the 1st token, expected: '3', found: '2'
2 Halted 0 ms 0 KB -

Subtask #5
0 / 21.0

# Verdict Execution time Memory Grader output
1 Incorrect 0 ms 212 KB 1st lines differ - on the 1st token, expected: '3', found: '2'
2 Halted 0 ms 0 KB -

Subtask #6
0 / 17.0

# Verdict Execution time Memory Grader output
1 Incorrect 0 ms 212 KB 1st lines differ - on the 1st token, expected: '3', found: '2'
2 Halted 0 ms 0 KB -

Subtask #7
0 / 14.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 212 KB Output is correct
2 Correct 2 ms 1748 KB Output is correct
3 Correct 24 ms 4132 KB Output is correct
4 Correct 16 ms 3656 KB Output is correct
5 Correct 30 ms 6460 KB Output is correct
6 Correct 26 ms 6464 KB Output is correct
7 Correct 27 ms 6560 KB Output is correct
8 Correct 28 ms 6460 KB Output is correct
9 Incorrect 27 ms 5824 KB 1st lines differ - on the 1st token, expected: '99999', found: '0'
10 Halted 0 ms 0 KB -

Subtask #8
0 / 16.0

# Verdict Execution time Memory Grader output
1 Correct 24 ms 5320 KB Output is correct
2 Correct 31 ms 5808 KB Output is correct
3 Correct 0 ms 212 KB Output is correct
4 Correct 0 ms 212 KB Output is correct
5 Correct 94 ms 19788 KB Output is correct
6 Correct 94 ms 19672 KB Output is correct
7 Correct 0 ms 212 KB Output is correct
8 Correct 50 ms 10384 KB Output is correct
9 Correct 61 ms 11212 KB Output is correct
10 Correct 25 ms 5336 KB Output is correct
11 Correct 29 ms 5952 KB Output is correct
12 Correct 1 ms 212 KB Output is correct
13 Correct 0 ms 212 KB Output is correct
14 Correct 1 ms 212 KB Output is correct
15 Correct 1 ms 212 KB Output is correct
16 Correct 0 ms 212 KB Output is correct
17 Correct 0 ms 212 KB Output is correct
18 Correct 26 ms 5464 KB Output is correct
19 Correct 29 ms 6460 KB Output is correct
20 Correct 24 ms 5444 KB Output is correct
21 Correct 28 ms 6076 KB Output is correct
22 Correct 25 ms 5472 KB Output is correct
23 Correct 27 ms 6080 KB Output is correct
24 Correct 1 ms 212 KB Output is correct
25 Correct 2 ms 1748 KB Output is correct
26 Correct 24 ms 4132 KB Output is correct
27 Correct 16 ms 3656 KB Output is correct
28 Correct 30 ms 6460 KB Output is correct
29 Correct 26 ms 6464 KB Output is correct
30 Correct 27 ms 6560 KB Output is correct
31 Correct 28 ms 6460 KB Output is correct
32 Incorrect 0 ms 212 KB 1st lines differ - on the 1st token, expected: '3', found: '2'
33 Halted 0 ms 0 KB -