CCC 2020 S2 Escape Room

    1#include <iostream>
    2#include <queue>
    3#include <vector>
    4using namespace std;
    5 
    6int main() {
    7    ios::sync_with_stdio(false);
    8    cin.tie(nullptr);
    9 
    10    int rows, columns;
    11    if (!(cin >> rows)) return 0;
    12    cin >> columns;
    13 
    14    const int cellCount = rows * columns;
    15    vector<int> value(cellCount);
    16    vector<vector<int>> cellsByProduct(cellCount + 1);
    17 
    18    for (int row = 1; row <= rows; ++row) {
    19        for (int column = 1; column <= columns; ++column) {
    20            const int index = (row - 1) * columns + column - 1;
    21            cin >> value[index];
    22            cellsByProduct[row * column].push_back(index);
    23        }
    24    }
    25 
    26    queue<int> pending;
    27    vector<char> visited(cellCount, false);
    28    pending.push(0);
    29    visited[0] = true;
    30 
    31    while (!pending.empty()) {
    32        const int index = pending.front();
    33        pending.pop();
    34 
    35        if (index == cellCount - 1) {
    36            cout << "yes\n";
    37            return 0;
    38        }
    39 
    40        const int jumpValue = value[index];
    41        if (jumpValue > cellCount) continue;
    42 
    43        for (const int next : cellsByProduct[jumpValue]) {
    44            if (!visited[next]) {
    45                visited[next] = true;
    46                pending.push(next);
    47            }
    48        }
    49        cellsByProduct[jumpValue].clear();
    50    }
    51 
    52    cout << "no\n";
    53    return 0;
    54}
    55