Time: 1079 ms (5.50%), Space: 153 MB (30.19%) - LeetHub

Author: Banzero1

307-range-sum-query-mutable/307-range-sum-query-mutable.cpp

@@ -0,0 +1,95 @@
+class NumArray {
+public:
+    vector<int>A,tree;
+    int n;
+    void build(int node, int start, int end)
+{
+    if(start == end)
+    {
+        // Leaf node will have a single element
+        tree[node] = A[start];
+    }
+    else
+    {
+        int mid = (start + end) / 2;
+        // Recurse on the left child
+        build(2*node+1, start, mid);
+        // Recurse on the right child
+        build(2*node+2, mid+1, end);
+        // Internal node will have the sum of both of its children
+        tree[node] = tree[2*node+2] + tree[2*node+1];
+    }
+}
+    
+ void update1(int node, int start, int end, int idx, int val)
+{
+    if(start == end)
+    {
+        // Leaf node
+        A[idx] = val;
+        tree[node] = val;
+    }
+    else
+    {
+        int mid = (start + end) / 2;
+        if(start <= idx and idx <= mid)
+        {
+            // If idx is in the left child, recurse on the left child
+            update1(2*node+1, start, mid, idx, val);
+        }
+        else
+        {
+            // if idx is in the right child, recurse on the right child
+            update1(2*node+2, mid+1, end, idx, val);
+        }
+        // Internal node will have the sum of both of its children
+        tree[node] = tree[2*node+1] + tree[2*node+2];
+    }
+}
+    
+ int query1(int node, int start, int end, int l, int r)
+{
+    if(r < start or end < l)
+    {
+        // range represented by a node is completely outside the given range
+        return 0;
+    }
+    if(l <= start and end <= r)
+    {
+        // range represented by a node is completely inside the given range
+        return tree[node];
+    }
+    // range represented by a node is partially inside and partially outside the given range
+    int mid = (start + end) / 2;
+    int p1 = query1(2*node+1, start, mid, l, r);
+    int p2 = query1(2*node+2, mid+1, end, l, r);
+    return (p1 + p2);
+}   
+    
+    
+    NumArray(vector<int>& nums) {
+        
+        //tree.resize(100000,0);
+        n=nums.size();
+         tree.resize(4*n,0);
+        A=nums;
+        build(0,0,n-1);
+    }
+    
+    void update(int index, int val) {
+        
+        return update1(0,0,n-1,index,val);
+    }
+    
+    int sumRange(int left, int right) {
+        
+        return query1(0,0,n-1,left,right);
+    }
+};
+
+/**
+ * Your NumArray object will be instantiated and called as such:
+ * NumArray* obj = new NumArray(nums);
+ * obj->update(index,val);
+ * int param_2 = obj->sumRange(left,right);
+ */