Valid Path

• Time : $O(ABC)$
• Space : $O(AB)$

string Solution::solve(int A, int B, int C, int D, vector<int> &E, vector<int> &F) {
    vector<vector<int>> vis(B+1,vector<int>(A+1));
    for(int i = 0; i <= B; i++) {
        for(int j = 0; j <= A; j++) {
            for(int k = 0; k < C and !vis[i][j]; k++) {
                if(sqrt(pow(E[k]-j, 2) + pow(F[k]-i, 2)) <= D) vis[i][j] = 1;
            }
        }
    }
    if(vis[0][0] or vis[B][A]) return "NO";
    queue<pair<int, int>> q;
    q.push({0,0});
    int dy[8] {-1,-1,-1,0,1,1,1,0}, dx[8]{-1,0,1,1,1,0,-1,-1};
    while(q.size()) {
        auto [y,x] = q.front(); q.pop();
        for(int i = 0; i < 8; i++) {
            int ny = y + dy[i], nx = x + dx[i];
            if(0 <= ny and ny <= B and 0 <= nx and nx <= A and !vis[ny][nx]) {
                vis[ny][nx] = 1;
                q.push({ny,nx});
            }
        }
    }
    return vis[B][A] ? "YES" : "NO";
}