oj.uz

Submission #629804

# Submission time Handle Problem Language Result Execution time Memory
629804 2022-08-15T07:57:08 Z spacewalker Catfish Farm (IOI22_fish) C++17
52 / 100
 858 ms 2097152 KB 
#include "fish.h"

#include <vector>
#include <bits/stdc++.h>

using namespace std;
using ll = long long;
constexpr ll INF = 1000000000000000000;

/*
    to make life easier, the value of a pier is (wt of fish behind/in front) - (wt of fish on pier)
    the path can be in a few states;
        - back-facing (pier at x=i that catches some fish at i-1)
        - front-facing (pier at x=i-1 that catches some fish at i)
    
    a back-facing path at y=h can move to
        - a back-facing path at some higher/same y value
        - a front-facing path at the same y value (do NOT count the - value of this pier, and ADD it to cancel the - of the ff path)

    a front-facing path at y=h can move to
        - a front-facing path at some lower/(same) y value
        - a back-facing path at some lower/same y value (do NOT count the + value of the first back-facing pier)
        - a back-facing path at a higher/(same) y value (do NOT count the + value of this pier)
        - stasis

    stasis can move to any back-facing path, or to stasis

    start the x-coordinates at 1; starting state is stasis at x=0
    pad 2 columns to the right; end state is stasis on last column

    then dp to get max weight path from start to end state
*/

long long max_weights(int N, int M, std::vector<int> X, std::vector<int> Y,
                      std::vector<int> W) {
    vector<vector<ll>> weights(N + 3, vector<ll>(N));
    for (int i = 0; i < M; ++i) {
        weights[X[i] + 1][Y[i]] = W[i];
    }
    vector<vector<ll>> columnSum = weights;
    for (int xc = 0; xc < columnSum.size(); ++xc) {
        for (int yc = 1; yc < N; ++yc) {
            columnSum[xc][yc] += columnSum[xc][yc-1];
        }
    }
    // needs xc > 0
    auto pierValue = [&] (int xc, int yc, int c1, int c2) {
        return c1 * columnSum[xc-1][yc] + c2 * columnSum[xc][yc];
    };
    vector<ll> stasisOpt(N + 3, -INF);
    vector<vector<ll>> backFaceOpt(N+3, vector<ll>(N, -INF)), frontFaceOpt(N+3, vector<ll>(N, -INF));
    // mod = -pierValue(xc, yc, 1, 0) is added to the entries
    vector<ll> nxtBackFaceModPrefMax(N, -INF), nxtBackFaceSufMax(N, -INF), nxtFrontFacePrefMax(N, -INF);
    stasisOpt[N+2] = 0;
    for (int xc = N+1; xc >= 0; --xc) {
        ll &s = stasisOpt[xc];
        for (int yc = 0; yc < N; ++yc) {
            ll &b = backFaceOpt[xc][yc], &f = frontFaceOpt[xc][yc];
            if (0 < xc && xc <= N) {
                // find value for the back-facing path here
                b = max(b, frontFaceOpt[xc+1][yc] + pierValue(xc, yc, 1, 1));
                /*
                for (int nyc = yc; nyc < N; ++nyc) {
                    b = max(b, backFaceOpt[xc+1][nyc] + pierValue(xc, yc, 1, -1));
                }
                */
                b = max(b, nxtBackFaceSufMax[yc] + pierValue(xc, yc, 1, -1));
            }
            if (2 <= xc && xc <= N + 1) {
                // find value for the front-facing path here
                f = max(f, stasisOpt[xc+1] + pierValue(xc, yc, -1, 1));
                /*
                for (int nyc = 0; nyc <= yc; ++nyc) {
                    f = max(f, frontFaceOpt[xc+1][nyc] + pierValue(xc, yc, -1, 1));
                    f = max(f, backFaceOpt[xc+1][nyc] + pierValue(xc, yc, -1, 1) - pierValue(xc+1, nyc, 1, 0));
                }
                */
                f = max(f, nxtFrontFacePrefMax[yc] + pierValue(xc, yc, -1, 1));
                f = max(f, nxtBackFaceModPrefMax[yc] + pierValue(xc, yc, -1, 1));
                /*
                for (int nyc = yc; nyc < N; ++nyc) {
                    f = max(f, backFaceOpt[xc+1][nyc] + pierValue(xc, yc, -1, 0));
                }
                */
                f = max(f, nxtBackFaceSufMax[yc] + pierValue(xc, yc, -1, 0));
            }
        }
        // find value for the stasis path here
        s = max(s, stasisOpt[xc+1]);
        for (int nyc = 0; nyc < N; ++nyc) {
            s = max(s, backFaceOpt[xc+1][nyc]);
        }
        // compute the prefix/suffix max arrays
        if (xc > 0) {
            nxtFrontFacePrefMax = frontFaceOpt[xc];
            for (int i = 1; i < N; ++i) nxtFrontFacePrefMax[i] = max(nxtFrontFacePrefMax[i-1], nxtFrontFacePrefMax[i]);
            nxtBackFaceModPrefMax = backFaceOpt[xc];
            for (int i = 0; i < N; ++i) nxtBackFaceModPrefMax[i] -= pierValue(xc, i, 1, 0);
            for (int i = 1; i < N; ++i) nxtBackFaceModPrefMax[i] = max(nxtBackFaceModPrefMax[i-1], nxtBackFaceModPrefMax[i]);
            nxtBackFaceSufMax = backFaceOpt[xc];
            for (int i = N - 2; i >= 0; --i) nxtBackFaceSufMax[i] = max(nxtBackFaceSufMax[i+1], nxtBackFaceSufMax[i]);
        }
    }
    return stasisOpt[0];
}

Compilation message

fish.cpp: In function 'long long int max_weights(int, int, std::vector<int>, std::vector<int>, std::vector<int>)':
fish.cpp:41:25: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::vector<long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   41 |     for (int xc = 0; xc < columnSum.size(); ++xc) {
      |                      ~~~^~~~~~~~~~~~~~~~~~

Subtask #1
0 / 3.0

# Verdict Execution time Memory Grader output
1 Runtime error 858 ms 2097152 KB Execution killed with signal 9
2 Halted 0 ms 0 KB -

Subtask #2
0 / 6.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 212 KB Output is correct
2 Runtime error 796 ms 2097152 KB Execution killed with signal 9
3 Halted 0 ms 0 KB -

Subtask #3
0 / 9.0

# Verdict Execution time Memory Grader output
1 Runtime error 763 ms 2097152 KB Execution killed with signal 9
2 Halted 0 ms 0 KB -

Subtask #4
14.0 / 14.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 212 KB Output is correct
2 Correct 0 ms 212 KB Output is correct
3 Correct 0 ms 212 KB Output is correct
4 Correct 0 ms 212 KB Output is correct
5 Correct 1 ms 212 KB Output is correct
6 Correct 0 ms 212 KB Output is correct
7 Correct 0 ms 212 KB Output is correct
8 Correct 0 ms 212 KB Output is correct
9 Correct 1 ms 980 KB Output is correct
10 Correct 4 ms 3156 KB Output is correct
11 Correct 1 ms 980 KB Output is correct
12 Correct 4 ms 3156 KB Output is correct
13 Correct 1 ms 468 KB Output is correct
14 Correct 4 ms 3156 KB Output is correct

Subtask #5
21.0 / 21.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 212 KB Output is correct
2 Correct 0 ms 212 KB Output is correct
3 Correct 0 ms 212 KB Output is correct
4 Correct 0 ms 212 KB Output is correct
5 Correct 1 ms 212 KB Output is correct
6 Correct 0 ms 212 KB Output is correct
7 Correct 0 ms 212 KB Output is correct
8 Correct 0 ms 212 KB Output is correct
9 Correct 1 ms 980 KB Output is correct
10 Correct 4 ms 3156 KB Output is correct
11 Correct 1 ms 980 KB Output is correct
12 Correct 4 ms 3156 KB Output is correct
13 Correct 1 ms 468 KB Output is correct
14 Correct 4 ms 3156 KB Output is correct
15 Correct 4 ms 3156 KB Output is correct
16 Correct 1 ms 448 KB Output is correct
17 Correct 19 ms 4172 KB Output is correct
18 Correct 19 ms 4168 KB Output is correct
19 Correct 15 ms 4164 KB Output is correct
20 Correct 15 ms 4180 KB Output is correct
21 Correct 15 ms 4164 KB Output is correct
22 Correct 26 ms 5208 KB Output is correct
23 Correct 6 ms 3284 KB Output is correct
24 Correct 10 ms 3796 KB Output is correct
25 Correct 4 ms 3156 KB Output is correct
26 Correct 6 ms 3284 KB Output is correct

Subtask #6
17.0 / 17.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 212 KB Output is correct
2 Correct 0 ms 212 KB Output is correct
3 Correct 0 ms 212 KB Output is correct
4 Correct 0 ms 212 KB Output is correct
5 Correct 1 ms 212 KB Output is correct
6 Correct 0 ms 212 KB Output is correct
7 Correct 0 ms 212 KB Output is correct
8 Correct 0 ms 212 KB Output is correct
9 Correct 1 ms 980 KB Output is correct
10 Correct 4 ms 3156 KB Output is correct
11 Correct 1 ms 980 KB Output is correct
12 Correct 4 ms 3156 KB Output is correct
13 Correct 1 ms 468 KB Output is correct
14 Correct 4 ms 3156 KB Output is correct
15 Correct 4 ms 3156 KB Output is correct
16 Correct 1 ms 448 KB Output is correct
17 Correct 19 ms 4172 KB Output is correct
18 Correct 19 ms 4168 KB Output is correct
19 Correct 15 ms 4164 KB Output is correct
20 Correct 15 ms 4180 KB Output is correct
21 Correct 15 ms 4164 KB Output is correct
22 Correct 26 ms 5208 KB Output is correct
23 Correct 6 ms 3284 KB Output is correct
24 Correct 10 ms 3796 KB Output is correct
25 Correct 4 ms 3156 KB Output is correct
26 Correct 6 ms 3284 KB Output is correct
27 Correct 330 ms 283076 KB Output is correct
28 Correct 75 ms 27048 KB Output is correct
29 Correct 422 ms 295556 KB Output is correct
30 Correct 398 ms 295556 KB Output is correct
31 Correct 399 ms 295540 KB Output is correct
32 Correct 88 ms 21712 KB Output is correct
33 Correct 450 ms 295592 KB Output is correct
34 Correct 405 ms 294988 KB Output is correct
35 Correct 378 ms 287240 KB Output is correct
36 Correct 391 ms 293500 KB Output is correct

Subtask #7
0 / 14.0

# Verdict Execution time Memory Grader output
1 Runtime error 763 ms 2097152 KB Execution killed with signal 9
2 Halted 0 ms 0 KB -

Subtask #8
0 / 16.0

# Verdict Execution time Memory Grader output
1 Runtime error 858 ms 2097152 KB Execution killed with signal 9
2 Halted 0 ms 0 KB -