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/* there is a concept called binary search on answer, the sole idea of binary search in not only about finding a target in a sorted array, but to half the sample space after each decision. */ //imagine slopes like we did in DSP class Solution { public: int findPeakElement(vector<int>& nums) { if(nums.size()==1) return 0; int n= nums.size(); if(nums[0] >nums[1]) return 0; if(nums[n-1] > nums[n-2]) return n-1; int s=0,e=nums.size()-1; while(s<=e){ int mid1=s+(e-s)/2; int mid2=mid1+1; if(nums[mid1] >nums[mid1-1] && nums[mid1] > nums[mid1+1]) return mid1; if(nums[mid1] <nums[mid2]){ s=mid1 +1; }else{ e=mid1; } } return -1; } };