General Sparse Table

codes/Sparse-General.cpp

@@ -0,0 +1,47 @@
+//Sparse-General
+//General Implementation of Sparse table with the template<class T> structure
+
+template<class T>
+class sparseTable
+{
+    public:
+    int n,k;
+    vector<vector<T>> table;
+    vector<T> logs;
+    function<T(T,T)> operation;
+    void init(int x,function<T(T,T)> _operation)
+    {  
+            operation=_operation;
+            n=x;
+            logs.resize(n+1);
+            logs[1]=0;
+            for(int i=2;i<=n;i++)
+                    logs[i]=logs[i/2]+1;
+            k=*max_element(logs.begin(),logs.end());
+            table.resize(k+1,vector<T>(n));
+    }
+
+    void build(vector<T> &arr)
+    {
+        for(int i=0;i<n;i++)
+                table[0][i]=arr[i];
+
+        for(int j=1;j<=k;j++)
+        {
+            for(int i=0;i+(1<<j)<=n;i++)
+                table[j][i]=operation(table[j-1][i],table[j-1][i+(1<<(j-1))]);
+        }
+    }
+    // 1 based indexing
+    T query(int l , int r)
+    {
+        assert(l<=r);
+        assert(l>=0 && r<n);
+        int j = logs[r - l + 1];
+        T answer = operation(table[j][l], table[j][r-(1<<j)+1]);
+        return answer;
+    }
+};
+
+
+// does not have a constructor, make an instance and then use the init method to use this