增加 problem 164

Algorithms/164. Maximum Gap/164. Maximum Gap.go

@@ -0,0 +1,85 @@
+package leetcode
+
+func maximumGap(nums []int) int {
+	if len(nums) < 2 {
+		return 0
+	}
+	quickSort__(nums, 0, len(nums)-1)
+
+	res := 0
+	for i := 0; i < len(nums)-1; i++ {
+		if (nums[i+1] - nums[i]) > res {
+			res = nums[i+1] - nums[i]
+		}
+	}
+	return res
+}
+
+func partition__(a []int, lo, hi int) int {
+	pivot := a[hi]
+	i := lo - 1
+	for j := lo; j < hi; j++ {
+		if a[j] < pivot {
+			i++
+			a[j], a[i] = a[i], a[j]
+		}
+	}
+	a[i+1], a[hi] = a[hi], a[i+1]
+	return i + 1
+}
+func quickSort__(a []int, lo, hi int) {
+	if lo >= hi {
+		return
+	}
+	p := partition__(a, lo, hi)
+	quickSort__(a, lo, p-1)
+	quickSort__(a, p+1, hi)
+}
+
+func maximumGap_(nums []int) int {
+
+	if nums == nil || len(nums) < 2 {
+		return 0
+	}
+
+	// m is the maximal number in nums
+	m := nums[0]
+	for i := 1; i < len(nums); i++ {
+		m = max(m, nums[i])
+	}
+
+	exp := 1 // 1, 10, 100, 1000 ...
+	R := 10  // 10 digits
+
+	aux := make([]int, len(nums))
+
+	for (m / exp) > 0 { // Go through all digits from LSB to MSB
+		count := make([]int, R)
+
+		for i := 0; i < len(nums); i++ {
+			count[(nums[i]/exp)%10]++
+		}
+
+		for i := 1; i < len(count); i++ {
+			count[i] += count[i-1]
+		}
+
+		for i := len(nums) - 1; i >= 0; i-- {
+			tmp := count[(nums[i]/exp)%10]
+			tmp--
+			aux[tmp] = nums[i]
+		}
+
+		for i := 0; i < len(nums); i++ {
+			nums[i] = aux[i]
+		}
+		exp *= 10
+	}
+
+	maxValue := 0
+	for i := 1; i < len(aux); i++ {
+		maxValue = max(maxValue, aux[i]-aux[i-1])
+	}
+
+	return maxValue
+}

Algorithms/164. Maximum Gap/164. Maximum Gap_test.go

@@ -0,0 +1,61 @@
+package leetcode
+
+import (
+	"fmt"
+	"testing"
+)
+
+type question164 struct {
+	para164
+	ans164
+}
+
+// para 是参数
+// one 代表第一个参数
+type para164 struct {
+	one []int
+}
+
+// ans 是答案
+// one 代表第一个答案
+type ans164 struct {
+	one int
+}
+
+func Test_Problem164(t *testing.T) {
+
+	qs := []question164{
+
+		question164{
+			para164{[]int{3, 6, 9, 1}},
+			ans164{3},
+		},
+		question164{
+			para164{[]int{1}},
+			ans164{0},
+		},
+
+		question164{
+			para164{[]int{}},
+			ans164{0},
+		},
+
+		question164{
+			para164{[]int{2, 10}},
+			ans164{8},
+		},
+
+		question164{
+			para164{[]int{2, 435, 214, 64321, 643, 7234, 7, 436523, 7856, 8}},
+			ans164{372202},
+		},
+	}
+
+	fmt.Printf("------------------------Leetcode Problem 164------------------------\n")
+
+	for _, q := range qs {
+		_, p := q.ans164, q.para164
+		fmt.Printf("【input】:%v       【output】:%v\n", p, maximumGap_(p.one))
+	}
+	fmt.Printf("\n\n\n")
+}

Algorithms/164. Maximum Gap/README.md

@@ -0,0 +1,43 @@
+# [164. Maximum Gap](https://leetcode.com/problems/maximum-gap/)
+
+## 题目
+
+Given an unsorted array, find the maximum difference between the successive elements in its sorted form.
+
+Return 0 if the array contains less than 2 elements.
+
+Example 1:
+
+```c
+Input: [3,6,9,1]
+Output: 3
+Explanation: The sorted form of the array is [1,3,6,9], either
+             (3,6) or (6,9) has the maximum difference 3.
+```
+
+Example 2:
+
+```c
+Input: [10]
+Output: 0
+Explanation: The array contains less than 2 elements, therefore return 0.
+```
+
+
+Note:
+
+- You may assume all elements in the array are non-negative integers and fit in the 32-bit signed integer range.
+- Try to solve it in linear time/space.
+
+
+## 题目大意
+
+在数组中找到 2 个数字之间最大的间隔。要求尽量用 O(1) 的时间复杂度和空间复杂度。
+
+虽然使用排序算法可以 AC 这道题。先排序，然后依次计算数组中两两数字之间的间隔，找到最大的一个间隔输出即可。
+
+这道题满足要求的做法是基数排序。
+
+
+
+