77 * Author : joney_000[let_me_start]
88 * Algorithm : Bit / fenwick tree
99 * Platform : Codeforces
10- * Ref : https://sanugupta.wordpress.com/2014/08/29/binary-indexed-tree-fenwick-tree/
10+ * Ref : 1.) https://sanugupta.wordpress.com/2014/08/29/binary-indexed-tree-fenwick-tree/
11+ * : 2.) https://www.topcoder.com/community/competitive-programming/tutorials/binary-indexed-trees/
1112 */
1213
13- public class A {
14+ public class BIT {
1415
1516 private InputStream inputStream ;
1617 private OutputStream outputStream ;
@@ -27,8 +28,8 @@ public class A{
2728 private final int INF = Integer .MAX_VALUE ;
2829 private final long INF_L = Long .MAX_VALUE / 10 ;
2930
30- public A (){}
31- public A (boolean stdIO )throws FileNotFoundException {
31+ public BIT (){}
32+ public BIT (boolean stdIO )throws FileNotFoundException {
3233 // stdIO = false;
3334 if (stdIO ){
3435 inputStream = System .in ;
@@ -41,12 +42,13 @@ public A(boolean stdIO)throws FileNotFoundException{
4142 out = new PrintWriter (outputStream );
4243 }
4344
44- 45+ final int MAX_TREE_SIZE = 200000 ;
46+ 4547 void run ()throws Exception {
4648 int n = i (); int q = i (); int m = i ();
4749 int qry [][] = new int [3 ][q + 1 ];// 0=>l, 1=> r, 2=>val
4850 int a [] = new int [n + 1 ];
49- 51+ initializeTree ( MAX_TREE_SIZE );
5052 for (int i = 1 ; i <= n ; i ++){
5153 a [i ] = i ();
5254 update (tree , i , a [i ]); // point update this time,
@@ -65,23 +67,31 @@ void run()throws Exception{
6567 }
6668
6769 for (int i = 1 ; i <= n ; i ++){
68- long res = qry (tree , i ); // case of point qry
70+ long res = query (tree , i ); // case of point qry
6971 out .write ("" +res +" " );
7072 }
7173
7274 }// end run
7375
74- final int MAX = 200000 ;
75- long tree [] = new long [ MAX + 5 ];
76+ private long [] tree ;
77+ private int treeSize ;
7678
77- void update (long tree [], int idx , long value ){ // idx to MAX
78- while (idx < MAX ){
79+ // time and space O(treeSize)
80+ private void initializeTree (int treeSize ){
81+ this .treeSize = treeSize ;
82+ tree = new long [treeSize ];
83+ }
84+ 85+ // range update, time: O(log treeSize)
86+ private void update (long tree [], int idx , long value ){
87+ while (idx < this .treeSize ){
7988 tree [idx ] += value ;
8089 idx += (idx & (-idx ));
8190 }
8291 }
8392
84- long qry (long tree [], int idx ){
93+ // range sum, time: O(log treeSize)
94+ private long query (long tree [], int idx ){
8595 long ret = 0 ;
8696 while (idx > 0 ){
8797 ret += tree [idx ];
@@ -199,7 +209,7 @@ private void closeResources(){
199209
200210 public static void main (String [] args ) throws java .lang .Exception {
201211
202- A driver = new A (true );
212+ BIT driver = new BIT (true );
203213 driver .run ();
204214 driver .closeResources ();
205215 }
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