General binary search in Java

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    We want to check mid and mid+1 elements. if(nums[mid] < nums[mid+1]), lo = mid + 1, otherwise hi = mid. The reason is that when there are even or odd number of elements, the mid element is always going to have a next one mid+1. We don't need to consider the case when there is less than 1 element as it is not valid case for this problem. Finally we return lo as it will always be a solution since it goes to mid+1 element in the first case, which is larger.

    public int findPeakElement(int[] nums) {
        int n = nums.length;
        int lo = 0, hi = n - 1;
        while(lo < hi) {
            int mid = lo + (hi - lo) / 2;
            if(nums[mid] < nums[mid+1]) {
                lo = mid + 1; 
            } else {
                hi = mid;
        return lo;

  • 0
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