Leetcode 278) First Bad Version

08 Sep 2021 in Algorithms

내 답안

/* The isBadVersion API is defined in the parent class VersionControl.
      boolean isBadVersion(int version); */

public class Solution extends VersionControl {
    public int firstBadVersion(int n) {
        if(n==1){return 1;}
        
        int l=0;
        //template2 version
        int r=n;
        
        while(l<r){
            int mid = l+(r-l)/2;
            if(!isBadVersion(mid) && isBadVersion(mid+1)){
                return mid+1;
            }else if(isBadVersion(mid)){
                r=mid;
            }else{
                l=mid+1;

            }
        }
        return 1;
    }
}

• api 덜 부르는 코드로 변경

/* The isBadVersion API is defined in the parent class VersionControl.
      boolean isBadVersion(int version); */

public class Solution extends VersionControl {
    public int firstBadVersion(int n) {
        if(n==1){return 1;}
        
        int l=0;
        //template2 version
        int r=n;
        
        while(l<r){
            int mid = l+(r-l)/2;
            boolean test=isBadVersion(mid);
            if(!test){
                if(isBadVersion(mid+1)){
                    return mid+1;
                }else{
                    l=mid+1;
                }
            }else if(test){
                r=mid;
            }
        }
        return 1;
    }
}

다른 답안

/* 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 start=0; int end=n;
        
       while(start<end)
       {
           int mid=start+(end-start)/2;
           if(isBadVersion(mid))
           {
               end=mid;
           }else{
               start=mid+1;
           }
       }
        return start;
    }
}

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