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Summing all the unique values of an array - JavaScript
Let’s say, we are required to write a JavaScript function that takes in an array of numbers with duplicate entries and sums all the duplicate entries to one index.
For example −
If the input array is −
const input = [1, 3, 1, 3, 5, 7, 5, 4];
Then the output should be −
const output = [2, 6, 7, 10, 4];
That means all the duplicate ones are summed to index 0 and all the duplicate threes are summed to index 1 and so on.
Example
Following is the code −
const input = [1, 3, 1, 3, 5, 7, 5, 4];
const mergeDuplicates = arr => {
const map = arr.reduce((acc, val) => {
if(acc.has(val)){
acc.set(val, acc.get(val) + 1);
}else{
acc.set(val, 1);
};
return acc;
}, new Map());
return Array.from(map, el => el[0] * el[1]);
};
console.log(mergeDuplicates(input));Output
This will produce the following output in console −
[ 2, 6, 10, 7, 4 ]
Updated on: 18-Sep-2020
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