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javascript Difference Array | Range update query in O(1)

Travinth Dayalaeaswaran answered on July 8, 2022 Popularity 1/10 Helpfulness 1/10

answer javascript Difference Array | Range update query in O(1)

javascript Difference Array | Range update query in O(1)

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<script>
// JavaScript code to demonstrate Difference Array
 
// Creates a diff array D[] for A[] and returns
// it after filling initial values.
function initializeDiffArray( A){
    let n = A.length;
 
    // We use one extra space because
    // update(l, r, x) updates D[r+1]
    let D= [];
 
    D[0] = A[0], D[n] = 0;
    for (let i = 1; i < n; i++)
        D[i] = A[i] - A[i - 1];
    return D;
}
 
// Does range update
function update(D, l, r, x){
    D[l] += x;
    D[r + 1] -= x;
    return D;
}
 
// Prints updated Array
function printArray( A, D){
    for (let i = 0; i < A.length; i++) {
        if (i == 0)
            A[i] = D[i];
 
        // Note that A[0] or D[0] decides
        // values of rest of the elements.
        else
            A[i] = D[i] + A[i - 1];
 
        document.write( A[i]+ " ");
    }
    document.write("<br>");
}
 
// Driver Code
// Array to be updated
let A = [ 10, 5, 20, 40 ];
 
// Create and fill difference Array
let D = initializeDiffArray(A);
 
// After below update(l, r, x), the
// elements should become 20, 15, 20, 40
D = update(D, 0, 1, 10);
printArray(A, D);
 
// After below updates, the
// array should become 30, 35, 70, 60
D = update(D, 1, 3, 20);
D = update(D, 2, 2, 30);
printArray(A, D);
 
</script>

Popularity 1/10 Helpfulness 1/10 Language javascript

Source: www.geeksforgeeks.org

Tags: difference javascript range

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Contributed on Jul 08 2022

Travinth Dayalaeaswaran

0 Answers Avg Quality 2/10

javascript Difference Array | Range update query in O(1)

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