#include #include using namespace std; struct UnionFind { int n; vector par; vector size_; UnionFind(int n_) : n(n_), par((size_t)n_), size_((size_t)n_,1){ for(int i = 0; n > i; i++)par[i] = i; } int root(int x){ if(par[x] == x)return x; return par[x] = root(par[x]); } void unite(int a,int b){ int ra = root(a); int rb = root(b); if(ra==rb)return; if(size(ra) > size(rb)) swap(ra,rb); par[ra] = rb; size_[rb] += size_[ra]; } bool same(int a, int b){ return root(a) == root(b); } int size(int a){ return size_[root(a)]; } void debug(){ for(int i = 0; n > i; i++){ cout << size_[root(i)] << " "; } cout << endl; return; } }; int main(){ int n,q;cin>>n>>q; UnionFind A(n); for(int i = 0; n > i; i++){ int x;cin>>x; if(x != -1){ A.unite(i,x-1); } } for(int i = 0; q > i; i++){ int a,b;cin>>a>>b; cout << (A.same(a-1, b-1) ? "Yes" : "No") << endl; } }