Added c++ solution for 1500-1599 / 1591.Strange Printer II

solution/1500-1599/1591.Strange Printer II/Solutions.cpp

@@ -0,0 +1,59 @@
+class Solution {
+    public:
+        bool isPrintable(vector<vector<int>>& targetGrid) {
+            int m = targetGrid.size(), n = targetGrid[0].size();
+
+            const int MAXC = 60;
+            vector<bool> seen(MAXC+1,false);
+            vector<int> minR(MAXC+1, m), maxR(MAXC+1, -1);
+            vector<int> minC(MAXC+1, n), maxC(MAXC+1, -1);
+
+            for(int i=0;i<m;i++){
+                for(int j=0;j<n;j++){
+                    int c = targetGrid[i][j];
+                    seen[c] = true;
+                    minR[c] = min(minR[c], i);
+                    maxR[c] = max(maxR[c], i);
+                    minC[c] = min(minC[c], j);
+                    maxC[c] = max(maxC[c], j);
+                }
+            }
+
+            vector<bitset<MAXC+1>> adj(MAXC+1);
+            vector<int> indeg(MAXC+1,0);
+            for(int c=1;c<=MAXC;c++){
+                if(!seen[c]) continue;
+                for(int i=minR[c]; i<=maxR[c]; i++){
+                    for(int j=minC[c]; j<=maxC[c]; j++){
+                        int d = targetGrid[i][j];
+                        if(d!=c && !adj[c].test(d)){
+                            adj[c].set(d);
+                            indeg[d]++;
+                        }
+                    }
+                }
+            }
+
+            // Kahn's algorithm on at most 60 nodes
+            queue<int> q;
+            int totalColors = 0;
+            for(int c=1;c<=MAXC;c++){
+                if(!seen[c]) continue;
+                totalColors++;
+                if(indeg[c]==0) q.push(c);
+            }
+
+            int seenCount = 0;
+            while(!q.empty()){
+                int u = q.front(); q.pop();
+                seenCount++;
+                for(int v=1;v<=MAXC;v++){
+                    if(adj[u].test(v) && --indeg[v]==0){
+                        q.push(v);
+                    }
+                }
+            }
+
+            return seenCount == totalColors;
+        }
+    };