Added c++ solution for 3500-3599 / 3534. Path Existence Queries in a Graph II

Author: ZAID646

solution/3500-3599/3534.Path Existence Queries in a Graph II/Solutions.cpp

@@ -0,0 +1,58 @@
+class Solution {
+    public:
+        vector<int> pathExistenceQueries(int n,
+                                         vector<int>& nums,
+                                         int maxDiff,
+                                         vector<vector<int>>& queries) {
+            vector<pair<int,int>> A(n);
+            for(int i=0;i<n;i++) A[i]={nums[i],i};
+            sort(A.begin(),A.end());
+            
+            vector<int> pos(n);
+            for(int i=0;i<n;i++) pos[A[i].second]=i;
+            
+            vector<int> R(n);
+            int r = 0;
+            for(int l=0; l<n; l++) {
+                while(r+1<n && A[r+1].first - A[l].first <= maxDiff) r++;
+                R[l] = r;
+            }
+            
+            int LOG = 0;
+            while((1<<LOG) <= n) LOG++;
+            vector<vector<int>> jump(LOG, vector<int>(n));
+            for(int i=0;i<n;i++) jump[0][i]=R[i];
+            for(int k=1;k<LOG;k++){
+                for(int i=0;i<n;i++){
+                    jump[k][i] = jump[k-1][ jump[k-1][i] ];
+                }
+            }
+            
+            auto minHops = [&](int p, int q)->int {
+                if(p>q) return INT_MAX/2;
+                if(p==q) return 0;
+                int hops = 0;
+                int cur = p;
+                for(int k=LOG-1;k>=0;k--){
+                    int nxt = jump[k][cur];
+                    if(nxt < q) {
+                        hops += (1<<k);
+                        cur = nxt;
+                    }
+                }
+                if(R[cur] < q) return INT_MAX/2;
+                return hops+1;
+            };
+            
+            vector<int> ans;
+            ans.reserve(queries.size());
+            for(auto &qr: queries){
+                int u=qr[0], v=qr[1];
+                int pu=pos[u], pv=pos[v];
+                if(pu>pv) swap(pu,pv);
+                int h = minHops(pu,pv);
+                ans.push_back(h >= INT_MAX/2 ? -1 : h);
+            }
+            return ans;
+        }
+    };