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Copy pathFindInMountainArray.java
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87 lines (53 loc) · 1.6 KB
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package com.binarySearch;
public class FindInMountainArray {
public static void main(String[] args) {
}
static int search(int[] arr , int target){
int peak = peakIndexInMountainArray(arr);
int firstTry = orderAgnosticBS(arr, target, 0, peak);
if ( firstTry != -1 ){
return firstTry;
}
return orderAgnosticBS(arr, target, peak+1, arr.length-1);
}
static int peakIndexInMountainArray(int[] arr) {
int start = 0;
int end = arr.length - 1;
int mid;
while( start < end ){
mid = start + (end - start) / 2;
if( arr[mid] > arr[mid + 1]){
end = mid;
}else{
start = mid + 1;
}
}
return start;
}
static int orderAgnosticBS(int[] arr, int target, int start, int end){
boolean isAscending = arr[end] > arr[start];
// while start is not greater than end
while(start <= end){
// better way to find the mid
int mid = start + (end - start) / 2;
// target is greater than mid
if(arr[mid] == target){
return mid;
}
if(isAscending){
if(target > arr[mid]){
start = mid + 1;
} else{
end = mid - 1;
}
}else{
if(target < arr[mid]){
start = mid + 1;
} else{
end = mid - 1;
}
}
}
return -1;
}
}