Question

How to implement a cumulative sum of numbers in an int array in TypeScript

Answer 1

// 0 : 0+1=1 : 0+1+2=3 : 0+1+2+3=6 : 0+1+2+3+4=10 : 0+1+2+3+4+5=15 ...

const cumulativeSum: any = (sum => (value: any) => sum += value)(0);

const arr: number[] = [0, 1, 2, 3, 4, 5, 6, 7, 8]; 

console.log(arr.map(cumulativeSum));

 
/*
run:
 
[0, 1, 3, 6, 10, 15, 21, 28, 36] 
 
*/
 

 

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Answer 2

const arr: number[] = [0, 1, 2, 3, 4, 5, 6, 7, 8]; 

let cumulativeSum: number[] = []
let sum = 0;
 
arr.forEach((e) => {
      sum = sum + e;
      cumulativeSum.push(sum);
})
 
console.log(cumulativeSum);

 
/*
run:
 
[0, 1, 3, 6, 10, 15, 21, 28, 36] 
 
*/

 

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