SOURCE

function a(n) {
    if (n===1) {
        return []
    }
    let a = [];
    let temp = [a];
    while(n-- > 2) {
        a[0] = [];
        a =a[0]
    }
    return temp;
}
// console.log(JSON.stringify(a(4)))

function get(target, arr) {
    for(let i = 0;i<arr.length;i++){
        for(let j = 0;j<arr.length;j++){
        if (i!==j && arr[i]+arr[j] === target) {
            return [i,j]
        }
      }
    }
}
console.log(11, get(12,[1,2,3,4,5,6,7]))