Create ParallelCoursesII.cpp

ParallelCoursesII.cpp

@@ -0,0 +1,83 @@
+class Solution {
+public:
+    int n,k;
+    vector<int>preq[15];
+    vector<int> dp;
+    int num_sems(int mask)
+    {
+        if(mask == (1<<n)-1)
+        {
+            return 0;
+        }
+        if(dp[mask] != -1)
+        {
+            return dp[mask];
+        }
+
+        vector<int>indeg(n,0);
+        for(int i = 0 ; i < n ; i++)
+        {
+            if(mask & (1 << i))
+            {
+                continue;
+            }
+            for(int j = 0 ; j < preq[i].size() ; j++)
+            {
+                indeg[preq[i][j]]++;  // All the courses dependent on i
+            }
+        }
+
+        int ok = 0;   // The courses which are avaiable to be taken on the current day , first no curces can be taken
+        for(int i = 0; i < n ; i++)
+        {
+            if(indeg[i] == 0 and !(mask&(1<<i)))
+            {
+                ok |= (1<<i);
+            }
+        }
+
+        // We have the number of cources available on that perticular day
+        int num_avail = __builtin_popcount(ok);
+        int taken = n+1;
+        // If num_avail > k, then we will have to check all possibilities 
+        int m = ok;
+        int s;
+        if(num_avail > k)
+        {
+            for(s = m; s ; s = (s-1)&m)
+            {
+                if(__builtin_popcount(s) != k)
+                {
+                    continue;
+                }
+                else
+                {
+                    taken = std::min(taken,1 + num_sems(mask|s));
+                }
+            }
+        }
+        else
+        {
+            taken = std::min(taken,1 + num_sems(mask|ok));
+        }
+
+        return dp[mask] = taken;
+    }
+
+
+    int minNumberOfSemesters(int N, vector<vector<int>>& dependencies, int K) {
+        n = N;
+        k = K;
+        dp.assign(1<<n,-1);
+        // memset(dp,-1,sizeof(dp));
+        for(int i = 0 ; i < dependencies.size() ; ++i)
+        {
+            dependencies[i][1] --;
+            dependencies[i][0] --;
+            preq[dependencies[i][0]].push_back(dependencies[i][1]);
+        }
+
+        int ans = num_sems(0);
+        return ans;
+    }
+};