-
Notifications
You must be signed in to change notification settings - Fork 0
/
FirstBadVersion.java
53 lines (48 loc) · 1.67 KB
/
FirstBadVersion.java
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
package com.algorithms.search.binary;
/**
* LeetCode 278. First Bad Version
*
* You are a product manager and currently leading a team to develop a new product.
* Unfortunately, the latest version of your product fails the quality check.
* Since each version is developed based on the previous version,
* all the versions after a bad version are also bad.
*
* Suppose you have n versions [1, 2, ..., n] and you want to find out the first bad one,
* which causes all the following ones to be bad.
*
* You are given an API bool isBadVersion(version) which will return whether version is bad.
* Implement a function to find the first bad version.
* You should minimize the number of calls to the API.
*/
public class FirstBadVersion {
public static int firstBadVersion(int n) {
int start = 1;
int end = n;
while (start <= end) {
int mid = start + (end - start) / 2;
boolean isBad = isBadVersion(mid);
if (isBad) {
if (mid == 1 || !isBadVersion(mid-1)) {
return mid;
} else {
end = mid - 1;
}
} else {
if (mid == n) {
return -1;
} else if (isBadVersion(mid+1)) {
return mid + 1;
} else {
start = mid + 1;
}
}
}
return -1;
}
public static boolean isBadVersion(int n) {
return n >= 1;
}
public static void main(String[] args) {
System.out.println(firstBadVersion(4));
}
}