leetcode-go/medium/275.h-index-ii.go

func hIndex(citations []int) int {
	// Target: find the first h that h <= citations[n-h]
	n := len(citations)
	beg, end := 0, n
	for beg < end {
		mid := beg + (end-beg)/2
		h, citation := n-mid, citations[mid]
		if h < citation {
			end = mid
		} else if citation < h {
			beg = mid + 1
		} else {
			return h
		}
	}
	return n - beg
}