Find out which combination of numbers in set add up to a given tơtal?

问题

I have set of numbers; example: [12, 13, 15, 18]. From which I have to find the elements whose sum is a specific "total value", for example: 25 is 12 + 13.

Edit: First of all thank you all for your valuable feedback but i think many of you misunderstood my question! My question is not just for "two combination" but for more than two. For example:

1 2 3 4 5 6 7 8 9 10 100

From the above list we need to get "119" here we need more than "two combination".

How can i write the code through bash script or JavaScript?

Kindly help.

回答1:

You could take a recursive approach and check every combination by using a short circuit for sums wich are greater than the given sum.

function getSum(numbers, sum) {
    function iter(index, right, left) {
        if (!left) return result.push(right);
        if (left < 0 || index >= numbers.length) return;
        iter(index + 1, [...right, numbers[index]], left - numbers[index]);
        iter(index + 1, right, left);
    }

    var result = [];
    iter(0, [], sum);
    return result;
}

getSum([12, 13, 15, 18], 25).forEach(a => console.log(...a));
console.log('--')
getSum([1, 2, 3, 4, 5], 10).forEach(a => console.log(...a));

回答2:

let orgArr=[12,13,14,11,15,18];

orgArr.filter((each,i,orgArr)=>orgArr[i+1]!==undefined?each+orgArr[i+1]===25?console.log(each,"..",orgArr[i+1]):"":"")

it will give you the pair which sum is 25

回答3:

You can do something simple using indexOf method.

function findComb(arr, sum) {
  for (let i = 0; i < arr.length - 1; i++) {
    let j = arr.indexOf(sum - arr[i], i);
    if (j !== -1) {
      return [arr[i], arr[j]]
    }
  }
}

console.log(findComb([12, 13, 15, 18], 25))

Note : Will return only the first combination and limited to 2 numbers.

回答4:

bash version:

#!/usr/bin/env bash

function find_sum {
    local sum=$1 first=$2; shift 2
    while test $# -gt 0; do
        for c; do
            if  test $sum = $(($first + $c)); then
                echo $sum = $first + $c
            fi
        done
        first=$1; shift
    done
}

find_sum 25 15 12 13 18

回答5:

Find all combinations using indexOf and Set to stock unique values:

function findComb(total, arr) {
  const output = new Set([]);
  arr.forEach((el, index) => {
    const i = arr.indexOf(total - el, index);
    if(i > -1) { output.add(el); output.add(arr[i]); }
  });
  return [...output];
}
console.log(findComb(25, [12, 13, 15, 18]));
console.log(findComb(25, [12, 13, 7, 15, 18, 12]));

回答6:

It is a variant of the knapsack problem, try to google for it. You can find the solution recursively in 2^n, or in n^2 using two-dimensional array for storing partial results.

来源：https://stackoverflow.com/questions/59467539/find-out-which-combination-of-numbers-in-set-add-up-to-a-given-t%c6%a1tal

标签

javascript

bash

math