Submission #1214055

#	Time	Username	Problem	Language	Result	Execution time	Memory
1214055		Nelt	Robot Contest (IOI23_robot)	C++20	0 / 100	67 ms	5960 KiB

robot

#include "robot.h"
#include <bits/stdc++.h>
#pragma GCC optimize("O3")
#define ll long long
#define endl "\n"
using namespace std;

int H, W;              // maze dimensions (provided by grader)
int PHASE = 0;         // 0 = BFS expansion, 1 = traceback
int L = 0;             // current BFS layer
int C = 2;             // marker color = L%4 + 2

void program_pulibot()
{
    vector<int> V = { -2, -1, 0, 1, 2, 3, 4, 5 };
    vector<int> S(5);
    auto mv = [&](int c) -> char {
        if (c == 2) return 'W';
        if (c == 3) return 'S';
        if (c == 4) return 'E';
        return 'N';
    };

    for (int s0 : V)
    for (int s1 : V)
    for (int s2 : V)
    for (int s3 : V)
    for (int s4 : V)
    {
        S[0] = s0; S[1] = s1; S[2] = s2; S[3] = s3; S[4] = s4;

        if (PHASE == 0)
        {
            // --- BFS expansion phase ---
            // 1) if on an unvisited cell at current layer, mark its parent pointer
            if (s0 == 0 && s1 == C)
            {
                bool moved = false;
                for (int d = 0; d < 4; d++)
                {
                    if (S[d+2] == 0)    // neighbor unvisited
                    {
                        int code = C +  (d%4);
                        set_instruction(S, code, mv(code));
                        moved = true;
                        break;
                    }
                }
                if (moved) continue;
            }

            // 2) detect first arrival at goal → switch to traceback
            if (s0 == 0 && s2 == -2 && s3 == -2)
            {
                PHASE = 1;
                set_instruction(S, 1, 'T');
                continue;
            }

            // 3) after sweeping all of layer L, advance to next layer
            //    (we see no S[1]==C anymore)
            bool any_at_layer = false;
            for (int x : V)
                if (x == C) { any_at_layer = true; break; }
            if (!any_at_layer)
            {
                L++;
                C = 2 + (L % 4);
            }

            // 4) on all other states, stay put
            set_instruction(S, 0, 'H');
        }
        else
        {
            // --- traceback phase ---
            if (s0 >= 2 && s0 <= 5)
            {
                set_instruction(S, 1, mv(s0));
            }
            else
            {
                set_instruction(S, 0, 'H');
            }
        }
    }
}

• Subtask 0: 0 / 0
• Subtask 1: 0 / 6
• Subtask 2: 0 / 10
• Subtask 3: 0 / 18
• Subtask 4: 0 / 20
• Subtask 5: 0 / 46