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| struct F {
int x, y, c;
F(int x, int y, int c): x(x), y(y), c(c) {}
};
class Solution {
private:
static constexpr int ds[5] = {1, 0, -1, 0, 1};
public:
int shortestPath(vector<vector<int>>& grid, int k) {
int m = grid.size(), n = grid[0].size();
if (m == 1 && n == 1) return 0;
if (k >= m + n - 3) return m + n - 2;
bool vis[m][n][k + 1];
memset(vis, false, sizeof(vis));
queue<F> q;
q.emplace(0, 0, k);
vis[0][0][k] = true;
int step = 0;
while (q.size()) {
++step;
int size = q.size();
while (size--) {
auto [x, y, c] = q.front(); q.pop();
for (int i = 0; i < 4; ++i) {
int nx = x + ds[i], ny = y + ds[i + 1];
if (nx < 0 || nx >= m || ny < 0 || ny >= n) continue;
if (nx == m - 1 && ny == n - 1) return step;
if (grid[nx][ny] == 0) {
if (vis[nx][ny][c]) continue;
q.emplace(nx, ny, c);
vis[nx][ny][c] = true;
} else if (c > 0 && !vis[nx][ny][c - 1]) {
q.emplace(nx, ny, c - 1);
vis[nx][ny][c - 1] = true;
}
}
}
}
return -1;
}
};
|