First Bad Version
给一个API, 找到一个返回false的数. 这个就是二分查找.
/* The isBadVersion API is defined in the parent class VersionControl.
boolean isBadVersion(int version); */
public class Solution extends VersionControl {
public int firstBadVersion(int n) {
int i = 1;
int j = n;
while(i<=j) {
int m = i + (j-i) / 2;
if(isBadVersion(m))
j = m - 1;
else
i = m + 1;
}
return i;
}
}