From 110cfae9ba09248f44519e2c132430995fb655ff Mon Sep 17 00:00:00 2001
From: Derwin1296 <34933140+Derwin1296@users.noreply.github.com>
Date: Wed, 8 Jan 2020 16:55:33 -0700
Subject: [PATCH] Allows update and queries in (log n time)
---
Uncategorized/Binary Indexed Tree/code.cpp | 120 +++++++++++++++++++++
1 file changed, 120 insertions(+)
create mode 100644 Uncategorized/Binary Indexed Tree/code.cpp
diff --git a/Uncategorized/Binary Indexed Tree/code.cpp b/Uncategorized/Binary Indexed Tree/code.cpp
new file mode 100644
index 00000000..de281180
--- /dev/null
+++ b/Uncategorized/Binary Indexed Tree/code.cpp
@@ -0,0 +1,120 @@
+import java.util.Random;
+// import visualization libraries {
+import org.algorithm_visualizer.*;
+// }
+
+class Main {
+ // define tracer variables {
+ Array1DTracer inputTracer = new Array1DTracer("Input");
+ Array1DTracer treeTracer = new Array1DTracer("Tree");
+ Array1DTracer rangeTracer = new Array1DTracer("Range");
+ LogTracer logTracer = new LogTracer("Console");
+ // }
+
+ // define input variables
+ int range[];
+ int parent[];
+ int input[];
+ int tree[];
+ int n;
+
+ // Finds parents for BIT
+ void findParent(){
+ for(int i = 1; i < n + 1; i++){
+ int p = i - (i & -i);
+ parent[i] = p;
+ }
+ }
+ // Correctly selects par to par + (i & -i)
+ void selectRange(int i){
+ int par = parent[i];
+ for(int ind = par; ind < par + (i & -i); ind++){
+ rangeTracer.select(ind);
+ }
+ }
+ void update(int val, int index, int n){
+ index = index + 1;
+ while(index <= n){
+ // Show updating of current index
+ logTracer.println("Currently updating index: " + index);
+ treeTracer.patch(index, tree[index] + val);
+ selectRange(index);
+ Tracer.delay();
+ // Deselect and delay
+ for(int i = 0; i < n; i++){
+ rangeTracer.deselect(i);
+ }
+ treeTracer.depatch(index);
+ Tracer.delay();
+ tree[index] += val;
+ index += (index & -index);
+ }
+ }
+
+ void solve(){
+ for(int i = 0; i < input.length; i++){
+ inputTracer.select(i);
+ logTracer.println("Adding " + input[i] + " to tree");
+ Tracer.delay();
+ update(input[i], i, n);
+ Tracer.delay();
+ inputTracer.deselect(i);
+ }
+ Random gen = new Random();
+ int left = gen.nextInt(n) + 1;
+ int right = Math.min(gen.nextInt(n - 1) + left + 1, n - 1);
+ logTracer.println("Finding sum between: (" + left + ", " + right + ")");
+ int r = query(right);
+ int l = query(left - 1);
+ logTracer.println("Left to right sum is: " + (r - l));
+ }
+
+ int query(int index){
+ int total = 0;
+ logTracer.println("Calculating sum for 0 to " + index);
+ index = index + 1;
+ while(index >= 1){
+ logTracer.println("Current total: " + total);
+ int nextIndex = index - (index & -index);
+ treeTracer.select(index);
+ // Select range represented by tree index and deselect afterwards
+ selectRange(index);
+ Tracer.delay();
+ for(int i = 0; i < n; i++){
+ rangeTracer.deselect(i);
+ }
+ total += tree[index];
+ index = nextIndex;
+ }
+ logTracer.println("Total sum is: " + total);
+ return total;
+ }
+
+ Main() {
+ // visualize {
+ Layout.setRoot(new VerticalLayout(new Commander[]{rangeTracer, inputTracer, treeTracer, logTracer}));
+ Random gen = new Random();
+ n = gen.nextInt(20) + 5;
+ // Loads neccessary arrays
+ input = new int[n];
+ range = new int[n];
+ tree = new int[n + 1];
+ parent = new int[n + 1];
+ // Calculate parents
+ findParent();
+ for(int i = 0; i < n; i++){
+ input[i] = gen.nextInt(30);
+ }
+ inputTracer.set(input);
+ treeTracer.set(tree);
+ rangeTracer.set(range);
+ // treeTracer.set(tree);
+ // Tracer.delay();
+ // }
+ solve();
+ }
+
+ public static void main(String[] args) {
+ new Main();
+ }
+}
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