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FindInMountainArray.java
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153 lines (110 loc) · 2.94 KB
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package com.vinay.practice.lc;
// https://leetcode.com/problems/find-in-mountain-array/description/
public class FindInMountainArray {
public static void main(String[] args) {
// TODO Auto-gerated method stub
int arr[] = {1,2,3,4,5,3,1};
//int ele = 3;
//int arr[] = {0,1,2,4,2,1};
int ele = 3;
int found = -1;
int peakIndex = findPeak(arr);
found = orderAgnosticBS(arr, 0, peakIndex, ele);
if(found == -1) {
found = orderAgnosticBS(arr, peakIndex, arr.length-1, ele);
}
System.out.println("Found at : " + found);
}
public static int findPeak(int arr[]) {
int start = 0;
int end = arr.length -1;
while(start < end) {
int mid = start + (end - start)/2;
if(arr[mid] > arr[mid+1]) {
end = mid;
} else if(arr[mid] < arr[mid+1]) {
start = mid+1;
}
}
return start;
}
public static int orderAgnosticBS(int[] arr, int start, int end, int target) {
// int start = 0;
// int end = arr.length-1;
boolean isAsc = arr[start] < arr[end];
while(start <= end) {
// System.out.println("s");
int mid = start + (end-start) / 2;
if(arr[mid] == target) {
return mid;
}
if(isAsc) {
if(target < arr[mid]) {
end = mid-1;
} else if(target > arr[mid]) {
start = mid+1;
}
} else {
if(target > arr[mid]) {
end = mid-1;
} else if(target < arr[mid]) {
start = mid+1;
}
}
}
return -1;
}
/*
// Leetcode solution
class Solution {
public int findInMountainArray(int target, MountainArray mountainArr) {
int peakIndex = findPeak(mountainArr);
int found = -1;
found = orderAgnosticBS(mountainArr, 0, peakIndex, target);
if(found == -1) {
found = orderAgnosticBS(mountainArr, peakIndex, mountainArr.length()-1, target);
}
return found;
}
public static int findPeak(MountainArray mountainArr) {
int start = 0;
int end = mountainArr.length()-1;
while(start < end) {
int mid = start + (end - start)/2;
if(mountainArr.get(mid) > mountainArr.get(mid+1)) {
end = mid;
} else if(mountainArr.get(mid) < mountainArr.get(mid+1)) {
start = mid+1;
}
}
return start;
}
public static int orderAgnosticBS(MountainArray mountainArr, int start, int end, int target) {
// int start = 0;
// int end = arr.length-1;
boolean isAsc = mountainArr.get(start) < mountainArr.get(end);
while(start <= end) {
// System.out.println("s");
int mid = start + (end-start) / 2;
if(mountainArr.get(mid) == target) {
return mid;
}
if(isAsc) {
if(target < mountainArr.get(mid)) {
end = mid-1;
} else if(target > mountainArr.get(mid)) {
start = mid+1;
}
} else {
if(target > mountainArr.get(mid)) {
end = mid-1;
} else if(target < mountainArr.get(mid)) {
start = mid+1;
}
}
}
return -1;
}
}
*/
}