**Task Score**

**Correctness**

**Performance**

A non-empty array A consisting of N integers is given. Array A represents numbers on a tape.

Any integer P, such that 0 < P < N, splits this tape into two non-empty parts: A[0], A[1], ..., A[P − 1] and A[P], A[P + 1], ..., A[N − 1].

The *difference* between the two parts is the value of: |(A[0] + A[1] + ... + A[P − 1]) − (A[P] + A[P + 1] + ... + A[N − 1])|

In other words, it is the absolute difference between the sum of the first part and the sum of the second part.

For example, consider array A such that:

`A[0] = 3 A[1] = 1 A[2] = 2 A[3] = 4 A[4] = 3`

We can split this tape in four places:

- P = 1, difference = |3 − 10| = 7

- P = 2, difference = |4 − 9| = 5

- P = 3, difference = |6 − 7| = 1

- P = 4, difference = |10 − 3| = 7

Write a function:

function solution(A);

that, given a non-empty array A of N integers, returns the minimal difference that can be achieved.

For example, given:

`A[0] = 3 A[1] = 1 A[2] = 2 A[3] = 4 A[4] = 3`

the function should return 1, as explained above.

Write an ** efficient** algorithm for the following assumptions:

- N is an integer within the range [2..100,000];
- each element of array A is an integer within the range [−1,000..1,000].

*not defined yet*

```
// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');
function solution(A) {
let leftNum = 0;
let rightNum = A.reduce((a,b) => a+b);
let answer = null;
for (let i=0; i<A.length-1; i++) {
leftNum += A[i];
rightNum -= A[i];
const diff = Math.abs(leftNum - rightNum)
if (answer === null || answer > diff) {
answer = diff
}
}
return answer
}
```

```
// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');
function solution(A) {
let leftNum = 0;
let rightNum = A.reduce((a,b) => a+b, 0);
let answer = Number.MAX_;
for (let i=0; i<A.length-1; i++) {
leftNum += A[i];
rightNum -= A[i];
const diff = Math.abs(leftNum - rightNum)
if (answer === null || answer > diff) {
answer = diff
}
}
return answer
}
```

```
// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');
function solution(A) {
let leftNum = 0;
let rightNum = A.reduce((a,b) => a+b, 0);
let answer = Number.MAX_SAFE_INTEGER;
for (let i=0; i<A.length-1; i++) {
leftNum += A[i];
rightNum -= A[i];
const diff = Math.abs(leftNum - rightNum)
if (answer === null || answer > diff) {
answer = diff
}
}
return answer
}
```

```
// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');
function solution(A) {
let leftNum = 0;
let rightNum = A.reduce((a,b) => a+b, 0);
let answer = -1;
for (let i=0; i<A.length-1; i++) {
leftNum += A[i];
rightNum -= A[i];
const diff = Math.abs(leftNum - rightNum)
if (answer === null || answer > diff) {
answer = diff
}
}
return answer
}
```

```
// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');
function solution(A) {
let leftSum = 0;
let rightSum = A.reduce((a,b) => a+b, 0);
let answer = -1;
for (let i=0; i<A.length-1; i++) {
leftSum += A[i];
rightSum -= A[i];
const diff = Math.abs(leftSum - rightSum)
if (answer === null || answer > diff) {
answer = diff
}
}
return answer
}
```

**Failed**

```
// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');
function solution(A) {
let leftSum = 0;
let rightSum = A.reduce((a,b) => a+b, 0);
let answer = -1;
for (let i=0; i<A.length-1; i++) {
leftSum += A[i];
rightSum -= A[i];
const diff = Math.abs(leftSum - rightSum)
if (answer > diff) {
answer = diff
}
}
return answer
}
```

**Example tests**

**WRONG ANSWER**, got -1 expected 1

**Passed**

```
// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');
function solution(A) {
let leftSum = 0;
let rightSum = A.reduce((a,b) => a+b, 0);
let answer = null;
for (let i=0; i<A.length-1; i++) {
leftSum += A[i];
rightSum -= A[i];
const diff = Math.abs(leftSum - rightSum)
if (answer === null || answer > diff) {
answer = diff
}
}
return answer
}
```

**Passed**

```
// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');
function solution(A) {
let leftSum = 0;
let rightSum = A.reduce((a,b) => a+b, 0);
let answer = null;
for (let i=0; i<A.length-1; i++) {
leftSum += A[i];
rightSum -= A[i];
const diff = Math.abs(leftSum - rightSum)
if (answer === null || answer > diff) {
answer = diff
}
}
return answer
}
```

**100**

```
// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');
function solution(A) {
let leftSum = 0;
let rightSum = A.reduce((a,b) => a+b, 0);
let answer = null;
for (let i=0; i<A.length-1; i++) {
leftSum += A[i];
rightSum -= A[i];
const diff = Math.abs(leftSum - rightSum)
if (answer === null || answer > diff) {
answer = diff
}
}
return answer
}
```

The solution obtained perfect score.

**O(N)**

**Correctness tests**

**OK**

**OK**

**OK**

**OK**

**OK**

**OK**

**OK**

**OK**

**OK**

**OK**

**OK**

**OK**

**OK**

**OK**

**Performance tests**

**OK**

**OK**

**OK**

**OK**

**OK**

**OK**

**OK**

**OK**

**OK**

**OK**