Tasks Details
easy
1.
Nesting
Determine whether a given string of parentheses (single type) is properly nested.
Task Score
25%
Correctness
50%
Performance
0%
A string S consisting of N characters is called properly nested if:
- S is empty;
- S has the form "(U)" where U is a properly nested string;
- S has the form "VW" where V and W are properly nested strings.
For example, string "(()(())())" is properly nested but string "())" isn't.
Write a function:
class Solution { public int solution(String S); }
that, given a string S consisting of N characters, returns 1 if string S is properly nested and 0 otherwise.
For example, given S = "(()(())())", the function should return 1 and given S = "())", the function should return 0, as explained above.
Write an efficient algorithm for the following assumptions:
- N is an integer within the range [0..1,000,000];
- string S is made only of the characters '(' and/or ')'.
Copyright 2009–2024 by Codility Limited. All Rights Reserved. Unauthorized copying, publication or disclosure prohibited.
Solution
Programming language used Java 8
Total time used 3 minutes
Effective time used 3 minutes
Notes
not defined yet
Task timeline
Code: 19:13:23 UTC,
java,
autosave
Code: 19:13:30 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(String S) {
Stack<String> stack = new Stack<>();
String[] strArr = S.split("");
for(String letter : strArr) {
if (letter.equals("(")) {
stack.push("(");
} else {
if (!stack.peek().equals("(")) return 0;
stack.pop();
}
}
return 1;
}
}
Analysis
Compile error
Solution.java:9: error: cannot find symbol Stack<String> stack = new Stack<>(); ^ symbol: class Stack location: class Solution Solution.java:9: error: cannot find symbol Stack<String> stack = new Stack<>(); ^ symbol: class Stack location: class Solution 2 errors
Code: 19:13:38 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(String S) {
Stack<String> stack = new Stack<>();
String[] strArr = S.split("");
for(String letter : strArr) {
if (letter.equals("(")) {
stack.push("(");
} else {
if (!stack.peek().equals("(")) return 0;
stack.pop();
}
}
return 1;
}
}
Analysis
expand all
Example tests
1.
0.008 s
OK
1.
0.004 s
RUNTIME ERROR,
tested program terminated with exit code 1
stderr:
Exception in thread "main" java.util.EmptyStackException at java.util.Stack.peek(Stack.java:102) at Solution.solution(Solution.java:17) at Exec.run(exec.java:46) at Exec.main(exec.java:31)
Code: 19:15:14 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(String S) {
Stack<String> stack = new Stack<>();
String[] strArr = S.split("");
for(String letter : strArr) {
if (letter.equals("(")) {
stack.push("(");
} else {
if (!stack.peek().equals("(")) return 0;
stack.pop();
}
}
return 1;
}
}
Code: 19:15:19 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(String S) {
Stack<String> stack = new Stack<>();
String[] strArr = S.split("");
for(String letter : strArr) {
if (letter.equals("(")) {
stack.push("(");
} else {
if (stack.size() == 0) return 0;
if (!stack.peek().equals("(")) return 0;
stack.pop();
}
}
return 1;
}
}
Analysis
Code: 19:15:27 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(String S) {
Stack<String> stack = new Stack<>();
String[] strArr = S.split("");
for(String letter : strArr) {
if (letter.equals("(")) {
stack.push("(");
} else {
if (stack.size() == 0) return 0;
if (!stack.peek().equals("(")) return 0;
stack.pop();
}
}
return 1;
}
}
Analysis
Code: 19:15:31 UTC,
java,
final,
score: 
25
// 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(String S) {
Stack<String> stack = new Stack<>();
String[] strArr = S.split("");
for(String letter : strArr) {
if (letter.equals("(")) {
stack.push("(");
} else {
if (stack.size() == 0) return 0;
if (!stack.peek().equals("(")) return 0;
stack.pop();
}
}
return 1;
}
}
Analysis summary
The following issues have been detected: wrong answers, timeout errors.
For example, for the input '' the solution returned a wrong answer (got 0 expected 1).
Analysis
expand all
Correctness tests
1.
0.008 s
OK
2.
0.008 s
OK
1.
0.008 s
WRONG ANSWER,
got 0 expected 1
simple_grouped
simple grouped positive and negative test, length=22
simple grouped positive and negative test, length=22
✘
WRONG ANSWER
got 1 expected 0
got 1 expected 0
1.
0.004 s
OK
2.
0.008 s
WRONG ANSWER,
got 1 expected 0
3.
0.008 s
OK
1.
0.008 s
OK
2.
0.008 s
OK
3.
0.008 s
OK
expand all
Performance tests
large1
simple large positive and negative test, 10K or 10K+1 ('s followed by 10K )'s
simple large positive and negative test, 10K or 10K+1 ('s followed by 10K )'s
✘
WRONG ANSWER
got 1 expected 0
got 1 expected 0
1.
0.092 s
OK
2.
0.092 s
WRONG ANSWER,
got 1 expected 0
3.
0.004 s
OK
large_full_ternary_tree
tree of the form T=(TTT) and depth 11, length=177K+
tree of the form T=(TTT) and depth 11, length=177K+
✘
TIMEOUT ERROR
running time: 0.75 sec., time limit: 0.42 sec.
running time: 0.75 sec., time limit: 0.42 sec.
1.
0.748 s
TIMEOUT ERROR,
running time: 0.75 sec., time limit: 0.42 sec.
2.
0.008 s
OK
multiple_full_binary_trees
sequence of full trees of the form T=(TT), depths [1..10..1], with/without unmatched ')' at the end, length=49K+
sequence of full trees of the form T=(TT), depths [1..10..1], with/without unmatched ')' at the end, length=49K+
✘
TIMEOUT ERROR
running time: 0.22 sec., time limit: 0.13 sec.
running time: 0.22 sec., time limit: 0.13 sec.
1.
0.216 s
TIMEOUT ERROR,
running time: 0.22 sec., time limit: 0.13 sec.
2.
0.224 s
TIMEOUT ERROR,
running time: 0.22 sec., time limit: 0.13 sec.
3.
0.008 s
OK
broad_tree_with_deep_paths
string of the form (TTT...T) of 300 T's, each T being '(((...)))' nested 200-fold, length=1 million
string of the form (TTT...T) of 300 T's, each T being '(((...)))' nested 200-fold, length=1 million
✘
TIMEOUT ERROR
running time: 4.98 sec., time limit: 2.32 sec.
running time: 4.98 sec., time limit: 2.32 sec.
1.
4.980 s
TIMEOUT ERROR,
running time: 4.98 sec., time limit: 2.32 sec.
2.
0.008 s
OK