Tasks Details
easy
Find the missing element in a given permutation.
Task Score
100%
Correctness
100%
Performance
100%
An array A consisting of N different integers is given. The array contains integers in the range [1..(N + 1)], which means that exactly one element is missing.
Your goal is to find that missing element.
Write a function:
class Solution { public int solution(int[] A); }
that, given an array A, returns the value of the missing element.
For example, given array A such that:
A[0] = 2 A[1] = 3 A[2] = 1 A[3] = 5the function should return 4, as it is the missing element.
Write an efficient algorithm for the following assumptions:
- N is an integer within the range [0..100,000];
- the elements of A are all distinct;
- each element of array A is an integer within the range [1..(N + 1)].
Copyright 2009–2025 by Codility Limited. All Rights Reserved. Unauthorized copying, publication or disclosure prohibited.
Solution
Programming language used Java 8
Time spent on task 4 minutes
Notes
not defined yet
Code: 10:41:41 UTC,
java,
verify,
result: Failed
// 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) {
// write your code in Java SE 8
int res = 0;
int max = A.length;
if(max==0)
return 1;
for(int i=0; i<max; i++){
res = (i+1)^A[i];
if(res != 0)
return res;
}
return res==0?(max+1):res;
}
}
Analysis
expand all
Example tests
1.
0.025 s
WRONG ANSWER,
got 3 expected 4
Code: 10:41:41 UTC,
java,
verify,
result: Failed
// 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) {
// write your code in Java SE 8
int res = 0;
int max = A.length;
if(max==0)
return 1;
for(int i=0; i<max; i++){
res = (i+1)^A[i];
if(res != 0)
return res;
}
return res==0?(max+1):res;
}
}
Analysis
expand all
Example tests
1.
0.025 s
WRONG ANSWER,
got 3 expected 4
Code: 10:42:34 UTC,
java,
verify,
result: Failed
// 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) {
// write your code in Java SE 8
int res = 0;
int max = A.length;
if(max==0)
return 1;
for(int i=0; i<max; i++){
res = (i+1)^A[i];
if(res != 0)
return (i+1);
}
return max+1;
}
}
Analysis
expand all
Example tests
1.
0.075 s
WRONG ANSWER,
got 1 expected 4
Code: 10:42:34 UTC,
java,
verify,
result: Failed
// 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) {
// write your code in Java SE 8
int res = 0;
int max = A.length;
if(max==0)
return 1;
for(int i=0; i<max; i++){
res = (i+1)^A[i];
if(res != 0)
return (i+1);
}
return max+1;
}
}
Analysis
expand all
Example tests
1.
0.075 s
WRONG ANSWER,
got 1 expected 4
Code: 10:43:21 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");
import java.util.Arrays;
class Solution {
public int solution(int[] A) {
// write your code in Java SE 8
int res = 0;
int max = A.length;
if(max==0)
return 1;
Arrays.sort(A);
for(int i=0; i<max; i++){
res = (i+1)^A[i];
if(res != 0)
return (i+1);
}
return max+1;
}
}
Analysis
Code: 10:43:21 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");
import java.util.Arrays;
class Solution {
public int solution(int[] A) {
// write your code in Java SE 8
int res = 0;
int max = A.length;
if(max==0)
return 1;
Arrays.sort(A);
for(int i=0; i<max; i++){
res = (i+1)^A[i];
if(res != 0)
return (i+1);
}
return max+1;
}
}
Analysis
Code: 10:43:34 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");
import java.util.Arrays;
class Solution {
public int solution(int[] A) {
// write your code in Java SE 8
int res = 0;
int max = A.length;
if(max==0)
return 1;
Arrays.sort(A);
for(int i=0; i<max; i++){
res = (i+1)^A[i];
if(res != 0)
return (i+1);
}
return max+1;
}
}
Analysis
Code: 10:43:34 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");
import java.util.Arrays;
class Solution {
public int solution(int[] A) {
// write your code in Java SE 8
int res = 0;
int max = A.length;
if(max==0)
return 1;
Arrays.sort(A);
for(int i=0; i<max; i++){
res = (i+1)^A[i];
if(res != 0)
return (i+1);
}
return max+1;
}
}
Analysis
Code: 10:43:42 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");
import java.util.Arrays;
class Solution {
public int solution(int[] A) {
// write your code in Java SE 8
int res = 0;
int max = A.length;
if(max==0)
return 1;
Arrays.sort(A);
for(int i=0; i<max; i++){
res = (i+1)^A[i];
if(res != 0)
return (i+1);
}
return max+1;
}
}Analysis summary
The solution obtained perfect score.
Analysis
Detected time complexity:
O(N) or O(N * log(N))
expand all
Correctness tests
1.
0.031 s
OK
2.
0.034 s
OK
1.
0.059 s
OK
2.
0.058 s
OK
1.
0.034 s
OK
2.
0.035 s
OK
1.
0.041 s
OK
2.
0.069 s
OK
3.
0.035 s
OK
1.
0.134 s
OK
expand all
Performance tests
1.
0.191 s
OK
1.
0.153 s
OK
1.
0.634 s
OK
2.
0.353 s
OK
3.
0.508 s
OK
1.
0.556 s
OK
1.
0.505 s
OK
Code: 10:43:42 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");
import java.util.Arrays;
class Solution {
public int solution(int[] A) {
// write your code in Java SE 8
int res = 0;
int max = A.length;
if(max==0)
return 1;
Arrays.sort(A);
for(int i=0; i<max; i++){
res = (i+1)^A[i];
if(res != 0)
return (i+1);
}
return max+1;
}
}Analysis summary
The solution obtained perfect score.
Analysis
Detected time complexity:
O(N) or O(N * log(N))
expand all
Correctness tests
1.
0.031 s
OK
2.
0.034 s
OK
1.
0.059 s
OK
2.
0.058 s
OK
1.
0.034 s
OK
2.
0.035 s
OK
1.
0.041 s
OK
2.
0.069 s
OK
3.
0.035 s
OK
1.
0.134 s
OK
expand all
Performance tests
1.
0.191 s
OK
1.
0.153 s
OK
1.
0.634 s
OK
2.
0.353 s
OK
3.
0.508 s
OK
1.
0.556 s
OK
1.
0.505 s
OK