add new solutions

solutions/8/q829/solution.go

@@ -0,0 +1,22 @@
+// Package q829 implements a solution for https://leetcode.com/problems/consecutive-numbers-sum/
+package q829
+
+import "math"
+
+func consecutiveNumbersSum(n int) int {
+	maxN := int(math.Sqrt(float64(n) * 2))
+	for maxN*(maxN+1)/2 <= n {
+		maxN++
+	}
+
+	cnt := 1
+	for nNums := maxN - 1; nNums > 1; nNums-- {
+		start := (n*2/nNums + 1 - nNums) / 2
+		if (start+start+nNums-1)*nNums/2 == n {
+			cnt++
+		}
+	}
+	return cnt
+}
+
+var _ = consecutiveNumbersSum

solutions/8/q852/solution.go

@@ -0,0 +1,17 @@
+// Package q852 implements a solution for https://leetcode.com/problems/peak-index-in-a-mountain-array/
+package q852
+
+func peakIndexInMountainArray(arr []int) int {
+	l, r := 0, len(arr)-1
+	for l < r {
+		m := (l + r) / 2
+		if arr[m] < arr[m+1] { // incrementing
+			l = m + 1
+		} else {
+			r = m
+		}
+	}
+	return l
+}
+
+var _ = peakIndexInMountainArray