Submission #1301316

#	Time	Username	Problem	Language	Result	Execution time	Memory
1301316		tamir1	Obstacles for a Llama (IOI25_obstacles)	C++20	0 / 100	54 ms	7468 KiB

obstacles

#include <bits/stdc++.h>
#include "obstacles.h"
using namespace std;

static int N, M;
static vector<int> Tval, Hval;
static vector<int> freecol;       // freecol[j] = 1 if T[0] > H[j]
static vector<int> nxt_block;     // nearest blocked cell to the right

void initialize(vector<int> T, vector<int> H) {
    Tval = T;
    Hval = H;
    N = Tval.size();
    M = Hval.size();

    freecol.assign(M, 0);
    nxt_block.assign(M, -1);

    int baseT = Tval[0];          // Only row 0 matters in Subtask 1

    for (int j = 0; j < M; j++)
        freecol[j] = (baseT >= Hval[j]) ? 0 : 1;

    int last = M-1;                 // sentinel for "no block to the right"
    for (int j = M - 1; j >= 0; j--) {
        if (freecol[j] == 1) {
            last = j;
        } else {
            nxt_block[j] = last - 1;  // first reachable free col to right - 1
        }
    }
}

bool can_reach(int L, int R, int S, int D) {
    // Subtask 1 guarantee: L = 0, R = M-1 always.

    // If nxt_block[a] >= b then columns a..b are all free.
    return nxt_block[min(S,D)] >= max(D,S);
}

• Subtask 0: 0 / 0
• Subtask 1: 0 / 10
• Subtask 2: 0 / 14
• Subtask 3: 0 / 13
• Subtask 4: 0 / 21
• Subtask 5: 0 / 25
• Subtask 6: 0 / 17