Tasks Details
medium
Find the minimal average of any slice containing at least two elements.
Task Score
100%
Correctness
100%
Performance
100%
A non-empty array A consisting of N integers is given. A pair of integers (P, Q), such that 0 ≤ P < Q < N, is called a slice of array A (notice that the slice contains at least two elements). The average of a slice (P, Q) is the sum of A[P] + A[P + 1] + ... + A[Q] divided by the length of the slice. To be precise, the average equals (A[P] + A[P + 1] + ... + A[Q]) / (Q − P + 1).
For example, array A such that:
A[0] = 4 A[1] = 2 A[2] = 2 A[3] = 5 A[4] = 1 A[5] = 5 A[6] = 8contains the following example slices:
- slice (1, 2), whose average is (2 + 2) / 2 = 2;
- slice (3, 4), whose average is (5 + 1) / 2 = 3;
- slice (1, 4), whose average is (2 + 2 + 5 + 1) / 4 = 2.5.
The goal is to find the starting position of a slice whose average is minimal.
Write a function:
class Solution { public int solution(int[] A); }
that, given a non-empty array A consisting of N integers, returns the starting position of the slice with the minimal average. If there is more than one slice with a minimal average, you should return the smallest starting position of such a slice.
For example, given array A such that:
A[0] = 4 A[1] = 2 A[2] = 2 A[3] = 5 A[4] = 1 A[5] = 5 A[6] = 8the 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 [−10,000..10,000].
Copyright 2009–2025 by Codility Limited. All Rights Reserved. Unauthorized copying, publication or disclosure prohibited.
Solution
Programming language used Java 21
Time spent on task 6 minutes
Notes
not defined yet
Code: 11:56:16 UTC,
java,
autosave
// you can also use imports, for example:
// import java.util.*;
// you can write to stdout for debugging purposes, e.g.
// System.out.println("this is a debug message");
class Solution {
public int solution(int[] A) {
int[] sums = new int[A.length+1];
for(int i =0; i < A.length; i++){
sums[i+1] = sums[i]+A[i];
}
float minAvg = 10001;
int minAvgStartPosition = -1;
for(int i =0; i < A.length-1; i++){
for(int j=i+1; j<A.length && j< i+3; j++){
int fromIdex = i;
int toIndex = j+1;
float newAvg = (sums[toIndex] - sums[fromIdex])/(float)(j-i+1);
if(newAvg < minAvg){
minAvg = newAvg;
minAvgStartPosition = i;
}
}
}
return minAvgStartPosition;
}
}
Code: 11:56:32 UTC,
java,
autosave
// you can also use imports, for example:
// import java.util.*;
// you can write to stdout for debugging purposes, e.g.
// System.out.println("this is a debug message");
class Solution {
public int solution(int[] A) {
int[] sums = new int[A.length+1];
for(int i =0; i < A.length; i++){
sums[i+1] = sums[i]+A[i];
}
float minAvg = 10001;
int minAvgStartPosition = -1;
for(int i =0; i < A.length-1; i++){
for(int j=i+1; j<A.length && j< i+3; j++){
int fromIdex = i;
int toIndex = j+1;
float newAvg = (sums[toIndex] - sums[fromIdex])/(float)(j-i+1);
if(newAvg < minAvg){
minAvg = newAvg;
minAvgStartPosition = i;
}
}
}
return minAvgStartPosition;
}
}
Code: 11:57:48 UTC,
java,
autosave
// you can also use imports, for example:
// import java.util.*;
// you can write to stdout for debugging purposes, e.g.
// System.out.println("this is a debug message");
class Solution {
public int solution(int[] A) {
int[] sums = new int[A.length+1];
for(int i =0; i < A.length; i++){
sums[i+1] = sums[i]+A[i];
}
float minAvg = 10001;
int minAvgStartPosition = -1;
for(int i =0; i < A.length-1; i++){
for(int j=i+1; j<A.length && j< i+3; j++){
int fromIdex = i;
int toIndex = j+1;
float newAvg = (sums[toIndex] - sums[fromIdex])/(float)(j-i+1);
if(newAvg < minAvg){
minAvg = newAvg;
minAvgStartPosition = i;
}
}
}
return minAvgStartPosition;
}
}
Code: 11:58:13 UTC,
java,
autosave
// you can also use imports, for example:
// import java.util.*;
// you can write to stdout for debugging purposes, e.g.
// System.out.println("this is a debug message");
class Solution {
public int solution(int[] A) {
int[] sums = new int[A.length+1];
for(int i =0; i < A.length; i++){
sums[i+1] = sums[i]+A[i];
}
float minAvg = 10001;
int minAvgStartPosition = -1;
for(int i =0; i < A.length-1; i++){
int twoSum =
for(int j=i+1; j<A.length && j< i+3; j++){
int fromIdex = i;
int toIndex = j+1;
float newAvg = (sums[toIndex] - sums[fromIdex])/(float)(j-i+1);
if(newAvg < minAvg){
minAvg = newAvg;
minAvgStartPosition = i;
}
}
}
return minAvgStartPosition;
}
}
Code: 11:58:27 UTC,
java,
autosave
// you can also use imports, for example:
// import java.util.*;
// you can write to stdout for debugging purposes, e.g.
// System.out.println("this is a debug message");
class Solution {
public int solution(int[] A) {
int[] sums = new int[A.length+1];
for(int i =0; i < A.length; i++){
sums[i+1] = sums[i]+A[i];
}
float minAvg = 10001;
int minAvgStartPosition = -1;
for(int i =0; i < A.length-1; i++){
int twoSum = A[i] + A[]
for(int j=i+1; j<A.length && j< i+3; j++){
int fromIdex = i;
int toIndex = j+1;
float newAvg = (sums[toIndex] - sums[fromIdex])/(float)(j-i+1);
if(newAvg < minAvg){
minAvg = newAvg;
minAvgStartPosition = i;
}
}
}
return minAvgStartPosition;
}
}
Code: 11:58:42 UTC,
java,
autosave
// you can also use imports, for example:
// import java.util.*;
// you can write to stdout for debugging purposes, e.g.
// System.out.println("this is a debug message");
class Solution {
public int solution(int[] A) {
int[] sums = new int[A.length+1];
for(int i =0; i < A.length; i++){
sums[i+1] = sums[i]+A[i];
}
float minAvg = 10001;
int minAvgStartPosition = -1;
for(int i =0; i < A.length-1; i++){
int twoSum = (A[i] + A[i+1])/2f
for(int j=i+1; j<A.length && j< i+3; j++){
int fromIdex = i;
int toIndex = j+1;
float newAvg = (sums[toIndex] - sums[fromIdex])/(float)(j-i+1);
if(newAvg < minAvg){
minAvg = newAvg;
minAvgStartPosition = i;
}
}
}
return minAvgStartPosition;
}
}
Code: 11:58:53 UTC,
java,
autosave
// you can also use imports, for example:
// import java.util.*;
// you can write to stdout for debugging purposes, e.g.
// System.out.println("this is a debug message");
class Solution {
public int solution(int[] A) {
int[] sums = new int[A.length+1];
for(int i =0; i < A.length; i++){
sums[i+1] = sums[i]+A[i];
}
float minAvg = 10001;
int minAvgStartPosition = -1;
for(int i =0; i < A.length-1; i++){
float twoSum = (A[i] + A[i+1])/2f;
for(int j=i+1; j<A.length && j< i+3; j++){
int fromIdex = i;
int toIndex = j+1;
float newAvg = (sums[toIndex] - sums[fromIdex])/(float)(j-i+1);
if(newAvg < minAvg){
minAvg = newAvg;
minAvgStartPosition = i;
}
}
}
return minAvgStartPosition;
}
}
Code: 11:59:04 UTC,
java,
autosave
// you can also use imports, for example:
// import java.util.*;
// you can write to stdout for debugging purposes, e.g.
// System.out.println("this is a debug message");
class Solution {
public int solution(int[] A) {
int[] sums = new int[A.length+1];
for(int i =0; i < A.length; i++){
sums[i+1] = sums[i]+A[i];
}
float minAvg = 10001;
int minAvgStartPosition = -1;
for(int i =0; i < A.length-1; i++){
float twoSum = (A[i] + A[i+1])/2f;
if(newAvg < minAvg){
minAvg = newAvg;
minAvgStartPosition = i;
}
for(int j=i+1; j<A.length && j< i+3; j++){
int fromIdex = i;
int toIndex = j+1;
float newAvg = (sums[toIndex] - sums[fromIdex])/(float)(j-i+1);
if(newAvg < minAvg){
minAvg = newAvg;
minAvgStartPosition = i;
}
}
}
return minAvgStartPosition;
}
}
Code: 11:59:16 UTC,
java,
autosave
// you can also use imports, for example:
// import java.util.*;
// you can write to stdout for debugging purposes, e.g.
// System.out.println("this is a debug message");
class Solution {
public int solution(int[] A) {
int[] sums = new int[A.length+1];
for(int i =0; i < A.length; i++){
sums[i+1] = sums[i]+A[i];
}
float minAvg = 10001;
int minAvgStartPosition = -1;
for(int i =0; i < A.length-1; i++){
float twoSum = (A[i] + A[i+1])/2f;
if(twoSum < minAvg){
minAvg = twoSum;
minAvgStartPosition = i;
}
if(i != )
for(int j=i+1; j<A.length && j< i+3; j++){
int fromIdex = i;
int toIndex = j+1;
float newAvg = (sums[toIndex] - sums[fromIdex])/(float)(j-i+1);
if(newAvg < minAvg){
minAvg = newAvg;
minAvgStartPosition = i;
}
}
}
return minAvgStartPosition;
}
}
Code: 11:59:26 UTC,
java,
autosave
// you can also use imports, for example:
// import java.util.*;
// you can write to stdout for debugging purposes, e.g.
// System.out.println("this is a debug message");
class Solution {
public int solution(int[] A) {
int[] sums = new int[A.length+1];
for(int i =0; i < A.length; i++){
sums[i+1] = sums[i]+A[i];
}
float minAvg = 10001;
int minAvgStartPosition = -1;
for(int i =0; i < A.length-1; i++){
float twoSum = (A[i] + A[i+1])/2f;
if(twoSum < minAvg){
minAvg = twoSum;
minAvgStartPosition = i;
}
if(i != A.length - 2)
for(int j=i+1; j<A.length && j< i+3; j++){
int fromIdex = i;
int toIndex = j+1;
float newAvg = (sums[toIndex] - sums[fromIdex])/(float)(j-i+1);
if(newAvg < minAvg){
minAvg = newAvg;
minAvgStartPosition = i;
}
}
}
return minAvgStartPosition;
}
}
Code: 11:59:45 UTC,
java,
autosave
// you can also use imports, for example:
// import java.util.*;
// you can write to stdout for debugging purposes, e.g.
// System.out.println("this is a debug message");
class Solution {
public int solution(int[] A) {
int[] sums = new int[A.length+1];
for(int i =0; i < A.length; i++){
sums[i+1] = sums[i]+A[i];
}
float minAvg = 10001;
int minAvgStartPosition = -1;
for(int i =0; i < A.length-1; i++){
float twoSum = (A[i] + A[i+1])/2f;
if(twoSum < minAvg){
minAvg = twoSum;
minAvgStartPosition = i;
}
if(i != A.length - 2){
}
for(int j=i+1; j<A.length && j< i+3; j++){
int fromIdex = i;
int toIndex = j+1;
float newAvg = (sums[toIndex] - sums[fromIdex])/(float)(j-i+1);
if(newAvg < minAvg){
minAvg = newAvg;
minAvgStartPosition = i;
}
}
}
return minAvgStartPosition;
}
}
Code: 12:00:12 UTC,
java,
autosave
// you can also use imports, for example:
// import java.util.*;
// you can write to stdout for debugging purposes, e.g.
// System.out.println("this is a debug message");
class Solution {
public int solution(int[] A) {
int[] sums = new int[A.length+1];
for(int i =0; i < A.length; i++){
sums[i+1] = sums[i]+A[i];
}
float minAvg = 10001;
int minAvgStartPosition = -1;
for(int i =0; i < A.length-1; i++){
float twoAvg = (A[i] + A[i+1])/2f;
if(twoAvg < minAvg){
minAvg = twoAvg;
minAvgStartPosition = i;
}
if(i != A.length - 2){
float threeAvg = (A[i] + A[i+1])/2f;
if(threeAvg < minAvg){
minAvg = threeAvg;
minAvgStartPosition = i;
}
}
for(int j=i+1; j<A.length && j< i+3; j++){
int fromIdex = i;
int toIndex = j+1;
float newAvg = (sums[toIndex] - sums[fromIdex])/(float)(j-i+1);
if(newAvg < minAvg){
minAvg = newAvg;
minAvgStartPosition = i;
}
}
}
return minAvgStartPosition;
}
}
Code: 12:00:28 UTC,
java,
verify,
result: Passed
// you can also use imports, for example:
// import java.util.*;
// you can write to stdout for debugging purposes, e.g.
// System.out.println("this is a debug message");
class Solution {
public int solution(int[] A) {
int[] sums = new int[A.length+1];
for(int i =0; i < A.length; i++){
sums[i+1] = sums[i]+A[i];
}
float minAvg = 10001;
int minAvgStartPosition = -1;
for(int i =0; i < A.length-1; i++){
float twoAvg = (A[i] + A[i+1])/2f;
if(twoAvg < minAvg){
minAvg = twoAvg;
minAvgStartPosition = i;
}
if(i != A.length - 2){
float threeAvg = (A[i] + A[i+1] + A[i+2])/3f;
if(threeAvg < minAvg){
minAvg = threeAvg;
minAvgStartPosition = i;
}
}
}
return minAvgStartPosition;
}
}
Analysis
Code: 12:00:43 UTC,
java,
autosave
// you can also use imports, for example:
// import java.util.*;
// you can write to stdout for debugging purposes, e.g.
// System.out.println("this is a debug message");
class Solution {
public int solution(int[] A) {
int[] sums = new int[A.length+1];
for(int i =0; i < A.length; i++){
sums[i+1] = sums[i]+A[i];
}
float minAvg = 10001;
int minAvgStartPosition = -1;
for(int i =0; i < A.length-1; i++){
float twoAvg = (A[i] + A[i+1])/2f;
if(twoAvg < minAvg){
minAvg = twoAvg;
minAvgStartPosition = i;
}
if(i != A.length - 2){
float threeAvg = (A[i] + A[i+1] + A[i+2])/3f;
if(threeAvg < minAvg){
minAvg = threeAvg;
minAvgStartPosition = i;
}
}
}
return minAvgStartPosition;
}
}
Code: 12:00:44 UTC,
java,
verify,
result: Passed
// you can also use imports, for example:
// import java.util.*;
// you can write to stdout for debugging purposes, e.g.
// System.out.println("this is a debug message");
class Solution {
public int solution(int[] A) {
int[] sums = new int[A.length+1];
for(int i =0; i < A.length; i++){
sums[i+1] = sums[i]+A[i];
}
float minAvg = 10001;
int minAvgStartPosition = -1;
for(int i =0; i < A.length-1; i++){
float twoAvg = (A[i] + A[i+1])/2f;
if(twoAvg < minAvg){
minAvg = twoAvg;
minAvgStartPosition = i;
}
if(i != A.length - 2){
float threeAvg = (A[i] + A[i+1] + A[i+2])/3f;
if(threeAvg < minAvg){
minAvg = threeAvg;
minAvgStartPosition = i;
}
}
}
return minAvgStartPosition;
}
}
Analysis
User test case 1:
[-3, -5, -8, -4, -10]
Code: 12:00:59 UTC,
java,
autosave
// you can also use imports, for example:
// import java.util.*;
// you can write to stdout for debugging purposes, e.g.
// System.out.println("this is a debug message");
class Solution {
public int solution(int[] A) {
float minAvg = 10001;
int minAvgStartPosition = -1;
for(int i =0; i < A.length-1; i++){
float twoAvg = (A[i] + A[i+1])/2f;
if(twoAvg < minAvg){
minAvg = twoAvg;
minAvgStartPosition = i;
}
if(i != A.length - 2){
float threeAvg = (A[i] + A[i+1] + A[i+2])/3f;
if(threeAvg < minAvg){
minAvg = threeAvg;
minAvgStartPosition = i;
}
}
}
return minAvgStartPosition;
}
}
Code: 12:01:25 UTC,
java,
verify,
result: Passed
// you can also use imports, for example:
// import java.util.*;
// you can write to stdout for debugging purposes, e.g.
// System.out.println("this is a debug message");
class Solution {
public int solution(int[] A) {
float minAvg = 10001;
int minAvgStartPosition = -1;
for(int i =0; i < A.length-1; i++){
float twoAvg = (A[i] + A[i+1])/2f;
if(twoAvg < minAvg){
minAvg = twoAvg;
minAvgStartPosition = i;
}
if(i != A.length - 2){
float threeAvg = (A[i] + A[i+1] + A[i+2])/3f;
if(threeAvg < minAvg){
minAvg = threeAvg;
minAvgStartPosition = i;
}
}
}
return minAvgStartPosition;
}
}
Analysis
User test case 1:
[-3, -5, -8, -4, -10]
Code: 12:01:29 UTC,
java,
final,
score:
100
// you can also use imports, for example:
// import java.util.*;
// you can write to stdout for debugging purposes, e.g.
// System.out.println("this is a debug message");
class Solution {
public int solution(int[] A) {
float minAvg = 10001;
int minAvgStartPosition = -1;
for(int i =0; i < A.length-1; i++){
float twoAvg = (A[i] + A[i+1])/2f;
if(twoAvg < minAvg){
minAvg = twoAvg;
minAvgStartPosition = i;
}
if(i != A.length - 2){
float threeAvg = (A[i] + A[i+1] + A[i+2])/3f;
if(threeAvg < minAvg){
minAvg = threeAvg;
minAvgStartPosition = i;
}
}
}
return minAvgStartPosition;
}
}
Analysis summary
The solution obtained perfect score.
Analysis
Detected time complexity:
O(N)
expand all
Correctness tests
1.
0.008 s
OK
2.
0.004 s
OK
3.
0.004 s
OK
4.
0.004 s
OK
1.
0.004 s
OK
2.
0.008 s
OK
1.
0.004 s
OK
1.
0.008 s
OK
1.
0.004 s
OK
2.
0.004 s
OK
3.
0.008 s
OK
expand all
Performance tests
1.
0.008 s
OK
1.
0.180 s
OK
2.
0.140 s
OK
1.
0.268 s
OK
1.
0.300 s
OK
2.
0.308 s
OK
3.
0.304 s
OK
1.
0.180 s
OK
2.
0.136 s
OK