leetcode: 1646. Get Maximum in Generated Array -- Array | Easy

leetcode/1646-get-maximum-in-generated-array/README.md

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+# 1646. Get Maximum in Generated Array
+
+You are given an integer `n`. An array `nums` of length `n + 1` is generated in the following way:
+
+- nums[0] = 0
+- nums[1] = 1
+- nums[2 * i] = nums[i] when 2 <= 2 * i <= n
+- nums[2 * i + 1] = nums[i] + nums[i + 1] when 2 <= 2 * i + 1 <= n
+
+*Return the **maximum** integer in the array `nums`.*
+
+**Example:**
+```
+Input: n = 7
+Output: 3
+Explanation: According to the given rules:
+  nums[0] = 0
+  nums[1] = 1
+  nums[(1 * 2) = 2] = nums[1] = 1
+  nums[(1 * 2) + 1 = 3] = nums[1] + nums[2] = 1 + 1 = 2
+  nums[(2 * 2) = 4] = nums[2] = 1
+  nums[(2 * 2) + 1 = 5] = nums[2] + nums[3] = 1 + 2 = 3
+  nums[(3 * 2) = 6] = nums[3] = 2
+  nums[(3 * 2) + 1 = 7] = nums[3] + nums[4] = 2 + 1 = 3
+Hence, nums = [0,1,1,2,1,3,2,3], and the maximum is 3.
+```
+
+**Constraints:**
+- `0 <= n <= 1000`

leetcode/1646-get-maximum-in-generated-array/get_maximum_generated.go

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+package leetcode
+
+func getMaximumGenerated(n int) int {
+	if n < 2 {
+		return n
+	}
+	nums, max := make([]int, n+1), 0
+	nums[1] = 1
+	for i := 1; i <= n/2; i++ {
+		nums[2*i] = nums[i]
+		if max < nums[i] {
+			max = nums[i]
+		}
+		if 2*i+1 > n {
+			return max
+		}
+		nums[2*i+1] = nums[i] + nums[i+1]
+		if max < nums[2*i+1] {
+			max = nums[2*i+1]
+		}
+	}
+	return max
+}

leetcode/1646-get-maximum-in-generated-array/get_maximum_generated_test.go

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+package leetcode
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestGetMaximumGenerated(t *testing.T) {
+	assert := assert.New(t)
+	for _, test := range tests {
+		assert.Equal(test.expected, getMaximumGenerated(test.input))
+	}
+}
+
+var tests = []struct {
+	input    int
+	expected int
+}{
+	{
+		input:    6,
+		expected: 3,
+	},
+	{
+		input:    100,
+		expected: 21,
+	},
+	{
+		input:    0,
+		expected: 0,
+	},
+	{
+		input:    1,
+		expected: 1,
+	},
+	{
+		input:    7,
+		expected: 3,
+	},
+	{
+		input:    1000,
+		expected: 89,
+	},
+}