I am trying to find what elements have been moved when comparing two arrays of strings. I want to find the elements that where explicitly moved and not moved as a side effect of other values being moved within the array. Please see example below:
const a = [1, 2, 3, 4, 5, 6];
const b = [1, 5, 6, 2, 3, 4];
findMovedElems(a, b) // returns [5, 6] even though [2, 3, 4,] have changed index too - that was caused as a side effect of 5, 6 being moved.
I didn't tested for others situations (like b with numbers not in a, duplicated numbers, etc.), but works on your example.
var a = [1, 2, 3, 4, 5, 6, 7, 8];
var b = [1, 5, 6, 2, 3, 4, 7, 8];
function findMovedElems(a, b) {
let result = [{"status" : 'OK', "arr" : []}]
// navigate over a and b
for (let i = 0, j = 0; i < a.length && j < b.length; i++, j++) {
if (a[i] === b[j]) {
result[result.length - 1].arr.push(a[i]);
continue;
}
result.push({"status" : 'MOVED', "arr" : [] });
// search for current b char on a
for(let i2 = i ; i2 < a.length; i2++) {
if (a[i2] !== b[j]) {
continue;
}
if (i2 === j) {
// a and b are synchonized again. Reset i and return to main loop
result[result.length - 1].status = 'OK';
j--;// warning: decrementing loop variable
i = j;// warning: changing loop variable
break;
}
// found move. Read from a and b when is equals
for (let i3 = i2; i3 < a.length && j < b.length; i3++, j++/* warning: incrementing other loop variable*/) {
if (a[i3] !== b[j]) {
break;
}
result[result.length - 1].arr.push(a[i3]);
}//for_i3
// Go back, because new array possition was readed, and should be read again on main loop
i--;// warning: decrementing loop variable
j--;// warning: decrementing loop variable
if (i === j) {
result.push({"status" : 'OK', "arr" : [] });
} else {
result.push({"status" : 'MOVED_SIDE_EFFECT', "arr" : [] });
}
break;
}//for_i2
}//for_i
return result;
}
console.log(JSON.stringify(findMovedElems(a, b)));output:
[{"status":"OK","arr":[1]},{"status":"MOVED","arr":[5,6]},{"status":"MOVED_SIDE_EFFECT","arr":[2,3,4]},{"status":"OK","arr":[7,8]}]