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Added Fenwick Tree Implementation #2570

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Merged
siriak merged 3 commits into from
Oct 20, 2021
Merged

Added Fenwick Tree Implementation #2570

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922228f
Added Fenwick Tree Implementation
KanakalathaVemuru Oct 11, 2021
79e263b
Update DataStructures/Trees/FenwickTree.java
siriak Oct 20, 2021
6d4a8d4
Merge branch 'master' into master
siriak Oct 20, 2021
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34 changes: 34 additions & 0 deletions DataStructures/Trees/FenwickTree.java
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Original file line number Diff line number Diff line change
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package DataStructures.Trees;

public class FenwickTree {
private int n;
private int fen_t[];

/* Constructor which takes the size of the array as a parameter */
public FenwickTree(int n) {
this.n = n;
this.fen_t = new int[n + 1];
}

/* A function which will add the element val at index i*/
public void update(int i, int val) {
// As index starts from 0, increment the index by 1
i += 1;
while (i <= n) {
fen_t[i] += val;
i += i & (-i);
}
}

/* A function which will return the cumulative sum from index 1 to index i*/
public int query(int i) {
// As index starts from 0, increment the index by 1
i += 1;
int cumSum = 0;
while (i > 0) {
cumSum += fen_t[i];
i -= i & (-i);
}
return cumSum;
}
}