Add solution 747

Author: halfrost

leetcode/0747.Largest-Number-At-Least-Twice-of-Others/747. Largest Number At Least Twice of Others.go

@@ -0,0 +1,20 @@
+package leetcode
+
+func dominantIndex(nums []int) int {
+	maxNum, flag, index := 0, false, 0
+	for i, v := range nums {
+		if v > maxNum {
+			maxNum = v
+			index = i
+		}
+	}
+	for _, v := range nums {
+		if v != maxNum && 2*v > maxNum {
+			flag = true
+		}
+	}
+	if flag {
+		return -1
+	}
+	return index
+}

leetcode/0747.Largest-Number-At-Least-Twice-of-Others/747. Largest Number At Least Twice of Others_test.go

@@ -0,0 +1,52 @@
+package leetcode
+
+import (
+	"fmt"
+	"testing"
+)
+
+type question747 struct {
+	para747
+	ans747
+}
+
+// para 是参数
+// one 代表第一个参数
+type para747 struct {
+	nums []int
+}
+
+// ans 是答案
+// one 代表第一个答案
+type ans747 struct {
+	one int
+}
+
+func Test_Problem747(t *testing.T) {
+
+	qs := []question747{
+
+		{
+			para747{[]int{3, 6, 1, 0}},
+			ans747{1},
+		},
+
+		{
+			para747{[]int{1, 2, 3, 4}},
+			ans747{-1},
+		},
+
+		{
+			para747{[]int{1}},
+			ans747{0},
+		},
+	}
+
+	fmt.Printf("------------------------Leetcode Problem 747------------------------\n")
+
+	for _, q := range qs {
+		_, p := q.ans747, q.para747
+		fmt.Printf("【input】:%v       【output】:%v\n", p, dominantIndex(p.nums))
+	}
+	fmt.Printf("\n\n\n")
+}

leetcode/0747.Largest-Number-At-Least-Twice-of-Others/README.md

@@ -0,0 +1,75 @@
+# [747. Largest Number At Least Twice of Others](https://leetcode.com/problems/largest-number-at-least-twice-of-others/)
+
+
+## 题目
+
+You are given an integer array `nums` where the largest integer is **unique**.
+
+Determine whether the largest element in the array is **at least twice** as much as every other number in the array. If it is, return *the **index** of the largest element, or return* `-1` *otherwise*.
+
+**Example 1:**
+
+```
+Input: nums = [3,6,1,0]
+Output: 1
+Explanation: 6 is the largest integer.
+For every other number in the array x, 6 is at least twice as big as x.
+The index of value 6 is 1, so we return 1.
+
+```
+
+**Example 2:**
+
+```
+Input: nums = [1,2,3,4]
+Output: -1
+Explanation: 4 is less than twice the value of 3, so we return -1.
+```
+
+**Example 3:**
+
+```
+Input: nums = [1]
+Output: 0
+Explanation: 1 is trivially at least twice the value as any other number because there are no other numbers.
+
+```
+
+**Constraints:**
+
+- `1 <= nums.length <= 50`
+- `0 <= nums[i] <= 100`
+- The largest element in `nums` is unique.
+
+## 题目大意
+
+给你一个整数数组 nums ，其中总是存在 唯一的 一个最大整数 。请你找出数组中的最大元素并检查它是否 至少是数组中每个其他数字的两倍 。如果是，则返回 最大元素的下标 ，否则返回 -1 。
+
+## 解题思路
+
+- 简单题。先扫描一遍找到最大值和下标。再扫描一遍检查最大值是否是其他数字的两倍。
+
+## 代码
+
+```go
+package leetcode
+
+func dominantIndex(nums []int) int {
+	maxNum, flag, index := 0, false, 0
+	for i, v := range nums {
+		if v > maxNum {
+			maxNum = v
+			index = i
+		}
+	}
+	for _, v := range nums {
+		if v != maxNum && 2*v > maxNum {
+			flag = true
+		}
+	}
+	if flag {
+		return -1
+	}
+	return index
+}
+```