PassingCars problem in codility using Java
I'm doing codility tasks. I am currently on the Passing Car quest - https://app.codility.com/programmers/lessons/5-prefix_sums/passing_cars/ ;
One of the performance test, I got "WRONG ANSWER, got -1794967296 expected -1"
(The performance test name is "large_big_answer
0..01..1, length = ~100,000")
Other tests were well done
I wonder how to correct this error
Here is my code
class Solution {
public int solution(int A) {
int mul = 0;
int cnt = 0;
for(int i = 0 ; i<A.length ; i++){
if(A[i] == 0) mul++;
else cnt = cnt+mul;
}
if(cnt>1000000000) return -1;
return cnt;
}
}
java performance
edited Nov 13 '18 at 10:12
Bas de Groot
540115
asked Nov 13 '18 at 10:05
AnalogAnalog
81
add a comment |
I'm doing codility tasks. I am currently on the Passing Car quest - https://app.codility.com/programmers/lessons/5-prefix_sums/passing_cars/ ;
One of the performance test, I got "WRONG ANSWER, got -1794967296 expected -1"
(The performance test name is "large_big_answer
0..01..1, length = ~100,000")
Other tests were well done
I wonder how to correct this error
Here is my code
class Solution {
public int solution(int A) {
int mul = 0;
int cnt = 0;
for(int i = 0 ; i<A.length ; i++){
if(A[i] == 0) mul++;
else cnt = cnt+mul;
}
if(cnt>1000000000) return -1;
return cnt;
}
}
java performance
edited Nov 13 '18 at 10:12
Bas de Groot
540115
asked Nov 13 '18 at 10:05
AnalogAnalog
81
UseBigInteger. Anintcan't hold such a large value.
– Nicholas K
Nov 13 '18 at 10:12
@NicholasK, this problem does not requireBigInteger. The problem space is such that one bails at < the size that can be handled in an integer.
– KevinO
Nov 13 '18 at 10:14
oh I see, thank you:)
– Analog
Nov 14 '18 at 0:08
add a comment |
I'm doing codility tasks. I am currently on the Passing Car quest - https://app.codility.com/programmers/lessons/5-prefix_sums/passing_cars/ ;
One of the performance test, I got "WRONG ANSWER, got -1794967296 expected -1"
(The performance test name is "large_big_answer
0..01..1, length = ~100,000")
Other tests were well done
I wonder how to correct this error
Here is my code
class Solution {
public int solution(int A) {
int mul = 0;
int cnt = 0;
for(int i = 0 ; i<A.length ; i++){
if(A[i] == 0) mul++;
else cnt = cnt+mul;
}
if(cnt>1000000000) return -1;
return cnt;
}
}
java performance
edited Nov 13 '18 at 10:12
Bas de Groot
540115
asked Nov 13 '18 at 10:05
AnalogAnalog
81
I'm doing codility tasks. I am currently on the Passing Car quest - https://app.codility.com/programmers/lessons/5-prefix_sums/passing_cars/ ;
One of the performance test, I got "WRONG ANSWER, got -1794967296 expected -1"
(The performance test name is "large_big_answer
0..01..1, length = ~100,000")
Other tests were well done
I wonder how to correct this error
Here is my code
class Solution {
public int solution(int A) {
int mul = 0;
int cnt = 0;
for(int i = 0 ; i<A.length ; i++){
if(A[i] == 0) mul++;
else cnt = cnt+mul;
}
if(cnt>1000000000) return -1;
return cnt;
}
}
java performance
java performance
edited Nov 13 '18 at 10:12
Bas de Groot
540115
asked Nov 13 '18 at 10:05
AnalogAnalog
81
edited Nov 13 '18 at 10:12
Bas de Groot
540115
asked Nov 13 '18 at 10:05
AnalogAnalog
81
edited Nov 13 '18 at 10:12
Bas de Groot
540115
edited Nov 13 '18 at 10:12
Bas de Groot
540115
edited Nov 13 '18 at 10:12
Bas de Groot
540115
540115
asked Nov 13 '18 at 10:05
AnalogAnalog
81
asked Nov 13 '18 at 10:05
AnalogAnalog
81
asked Nov 13 '18 at 10:05
AnalogAnalog
81
81
UseBigInteger. Anintcan't hold such a large value.
– Nicholas K
Nov 13 '18 at 10:12
@NicholasK, this problem does not requireBigInteger. The problem space is such that one bails at < the size that can be handled in an integer.
– KevinO
Nov 13 '18 at 10:14
oh I see, thank you:)
– Analog
Nov 14 '18 at 0:08
add a comment |
UseBigInteger. Anintcan't hold such a large value.
– Nicholas K
Nov 13 '18 at 10:12
@NicholasK, this problem does not requireBigInteger. The problem space is such that one bails at < the size that can be handled in an integer.
– KevinO
Nov 13 '18 at 10:14
oh I see, thank you:)
– Analog
Nov 14 '18 at 0:08
Use
BigInteger. An int can't hold such a large value.– Nicholas K
Nov 13 '18 at 10:12
Use
BigInteger. An int can't hold such a large value.– Nicholas K
Nov 13 '18 at 10:12
@NicholasK, this problem does not require
BigInteger. The problem space is such that one bails at < the size that can be handled in an integer.– KevinO
Nov 13 '18 at 10:14
@NicholasK, this problem does not require
BigInteger. The problem space is such that one bails at < the size that can be handled in an integer.– KevinO
Nov 13 '18 at 10:14
oh I see, thank you:)
– Analog
Nov 14 '18 at 0:08
oh I see, thank you:)
– Analog
Nov 14 '18 at 0:08
add a comment |
1 Answer
1
active
oldest
votes
The issue, as @Nicholas K noted, does have to do with an overflow.
Move the check for the if (cnt > 1_000_000_000) into the for loop. The requirements are:
The function should return −1 if the number of pairs of passing
cars exceeds 1,000,000,000.
As such, as soon as the number of pairs exceeds the count, then stop.
So,
public int solution(int A) {
int mul = 0;
int cnt = 0;
for(int i = 0 ; i<A.length ; i++){
if(A[i] == 0) mul++;
else cnt = cnt+mul;
if(cnt>1000000000) return -1;
}
return cnt;
}
Here is a test case that shows the failure:
@Test
public void testHalfEach() {
final int inp = new int[100_000];
final int exp = -1;
Arrays.fill(inp, 0, 50_000, 0);
Arrays.fill(inp, 50_000, 100_000, 1);
validate(inp, exp);
}
private void validate(int inp, int exp)
{
PassingCars prog = new PassingCars();
int ans = prog.solution(inp);
assertEquals(exp, ans);
}
Changing the location of the check will allow this test to pass.
answered Nov 13 '18 at 10:20
KevinOKevinO
3,09131628
add a comment |
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1 Answer
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votes
The issue, as @Nicholas K noted, does have to do with an overflow.
Move the check for the if (cnt > 1_000_000_000) into the for loop. The requirements are:
The function should return −1 if the number of pairs of passing
cars exceeds 1,000,000,000.
As such, as soon as the number of pairs exceeds the count, then stop.
So,
public int solution(int A) {
int mul = 0;
int cnt = 0;
for(int i = 0 ; i<A.length ; i++){
if(A[i] == 0) mul++;
else cnt = cnt+mul;
if(cnt>1000000000) return -1;
}
return cnt;
}
Here is a test case that shows the failure:
@Test
public void testHalfEach() {
final int inp = new int[100_000];
final int exp = -1;
Arrays.fill(inp, 0, 50_000, 0);
Arrays.fill(inp, 50_000, 100_000, 1);
validate(inp, exp);
}
private void validate(int inp, int exp)
{
PassingCars prog = new PassingCars();
int ans = prog.solution(inp);
assertEquals(exp, ans);
}
Changing the location of the check will allow this test to pass.
answered Nov 13 '18 at 10:20
KevinOKevinO
3,09131628
add a comment |
The issue, as @Nicholas K noted, does have to do with an overflow.
Move the check for the if (cnt > 1_000_000_000) into the for loop. The requirements are:
The function should return −1 if the number of pairs of passing
cars exceeds 1,000,000,000.
As such, as soon as the number of pairs exceeds the count, then stop.
So,
public int solution(int A) {
int mul = 0;
int cnt = 0;
for(int i = 0 ; i<A.length ; i++){
if(A[i] == 0) mul++;
else cnt = cnt+mul;
if(cnt>1000000000) return -1;
}
return cnt;
}
Here is a test case that shows the failure:
@Test
public void testHalfEach() {
final int inp = new int[100_000];
final int exp = -1;
Arrays.fill(inp, 0, 50_000, 0);
Arrays.fill(inp, 50_000, 100_000, 1);
validate(inp, exp);
}
private void validate(int inp, int exp)
{
PassingCars prog = new PassingCars();
int ans = prog.solution(inp);
assertEquals(exp, ans);
}
Changing the location of the check will allow this test to pass.
answered Nov 13 '18 at 10:20
KevinOKevinO
3,09131628
add a comment |
The issue, as @Nicholas K noted, does have to do with an overflow.
Move the check for the if (cnt > 1_000_000_000) into the for loop. The requirements are:
The function should return −1 if the number of pairs of passing
cars exceeds 1,000,000,000.
As such, as soon as the number of pairs exceeds the count, then stop.
So,
public int solution(int A) {
int mul = 0;
int cnt = 0;
for(int i = 0 ; i<A.length ; i++){
if(A[i] == 0) mul++;
else cnt = cnt+mul;
if(cnt>1000000000) return -1;
}
return cnt;
}
Here is a test case that shows the failure:
@Test
public void testHalfEach() {
final int inp = new int[100_000];
final int exp = -1;
Arrays.fill(inp, 0, 50_000, 0);
Arrays.fill(inp, 50_000, 100_000, 1);
validate(inp, exp);
}
private void validate(int inp, int exp)
{
PassingCars prog = new PassingCars();
int ans = prog.solution(inp);
assertEquals(exp, ans);
}
Changing the location of the check will allow this test to pass.
answered Nov 13 '18 at 10:20
KevinOKevinO
3,09131628
The issue, as @Nicholas K noted, does have to do with an overflow.
Move the check for the if (cnt > 1_000_000_000) into the for loop. The requirements are:
The function should return −1 if the number of pairs of passing
cars exceeds 1,000,000,000.
As such, as soon as the number of pairs exceeds the count, then stop.
So,
public int solution(int A) {
int mul = 0;
int cnt = 0;
for(int i = 0 ; i<A.length ; i++){
if(A[i] == 0) mul++;
else cnt = cnt+mul;
if(cnt>1000000000) return -1;
}
return cnt;
}
Here is a test case that shows the failure:
@Test
public void testHalfEach() {
final int inp = new int[100_000];
final int exp = -1;
Arrays.fill(inp, 0, 50_000, 0);
Arrays.fill(inp, 50_000, 100_000, 1);
validate(inp, exp);
}
private void validate(int inp, int exp)
{
PassingCars prog = new PassingCars();
int ans = prog.solution(inp);
assertEquals(exp, ans);
}
Changing the location of the check will allow this test to pass.
answered Nov 13 '18 at 10:20
KevinOKevinO
3,09131628
answered Nov 13 '18 at 10:20
KevinOKevinO
3,09131628
answered Nov 13 '18 at 10:20
KevinOKevinO
3,09131628
answered Nov 13 '18 at 10:20
KevinOKevinO
3,09131628
3,09131628
add a comment |
add a comment |
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Use
BigInteger. Anintcan't hold such a large value.– Nicholas K
Nov 13 '18 at 10:12
@NicholasK, this problem does not require
BigInteger. The problem space is such that one bails at < the size that can be handled in an integer.– KevinO
Nov 13 '18 at 10:14
oh I see, thank you:)
– Analog
Nov 14 '18 at 0:08