添加 problem 744

Author: halfrost

Algorithms/0744. Find Smallest Letter Greater Than Target/744. Find Smallest Letter Greater Than Target.go

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+package leetcode
+
+func nextGreatestLetter(letters []byte, target byte) byte {
+	low, high := 0, len(letters)-1
+	for low <= high {
+		mid := low + (high-low)>>1
+		if letters[mid] > target {
+			high = mid - 1
+		} else {
+			low = mid + 1
+		}
+	}
+	find := letters[low%len(letters)]
+	if find <= target {
+		return letters[0]
+	}
+	return find
+}

Algorithms/0744. Find Smallest Letter Greater Than Target/744. Find Smallest Letter Greater Than Target_test.go

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+package leetcode
+
+import (
+	"fmt"
+	"testing"
+)
+
+type question744 struct {
+	para744
+	ans744
+}
+
+// para 是参数
+// one 代表第一个参数
+type para744 struct {
+	letters []byte
+	target  byte
+}
+
+// ans 是答案
+// one 代表第一个答案
+type ans744 struct {
+	one byte
+}
+
+func Test_Problem744(t *testing.T) {
+
+	qs := []question744{
+
+		question744{
+			para744{[]byte{'c', 'f', 'j'}, 'a'},
+			ans744{'c'},
+		},
+
+		question744{
+			para744{[]byte{'c', 'f', 'j'}, 'c'},
+			ans744{'f'},
+		},
+
+		question744{
+			para744{[]byte{'c', 'f', 'j'}, 'd'},
+			ans744{'f'},
+		},
+
+		question744{
+			para744{[]byte{'c', 'f', 'j'}, 'g'},
+			ans744{'j'},
+		},
+
+		question744{
+			para744{[]byte{'c', 'f', 'j'}, 'j'},
+			ans744{'c'},
+		},
+
+		question744{
+			para744{[]byte{'c', 'f', 'j'}, 'k'},
+			ans744{'c'},
+		},
+	}
+
+	fmt.Printf("------------------------Leetcode Problem 744------------------------\n")
+
+	for _, q := range qs {
+		_, p := q.ans744, q.para744
+		fmt.Printf("【input】:%v       【output】:%v\n", p, nextGreatestLetter(p.letters, p.target))
+	}
+	fmt.Printf("\n\n\n")
+}

Algorithms/0744. Find Smallest Letter Greater Than Target/README.md

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+# [744. Find Smallest Letter Greater Than Target](https://leetcode.com/problems/find-smallest-letter-greater-than-target/)
+
+
+## 题目:
+
+Given a list of sorted characters `letters` containing only lowercase letters, and given a target letter `target`, find the smallest element in the list that is larger than the given target.
+
+Letters also wrap around. For example, if the target is `target = 'z'` and `letters = ['a', 'b']`, the answer is `'a'`.
+
+**Examples:**
+
+    Input:
+    letters = ["c", "f", "j"]
+    target = "a"
+    Output: "c"
+    
+    Input:
+    letters = ["c", "f", "j"]
+    target = "c"
+    Output: "f"
+    
+    Input:
+    letters = ["c", "f", "j"]
+    target = "d"
+    Output: "f"
+    
+    Input:
+    letters = ["c", "f", "j"]
+    target = "g"
+    Output: "j"
+    
+    Input:
+    letters = ["c", "f", "j"]
+    target = "j"
+    Output: "c"
+    
+    Input:
+    letters = ["c", "f", "j"]
+    target = "k"
+    Output: "c"
+
+**Note:**
+
+1. `letters` has a length in range `[2, 10000]`.
+2. `letters` consists of lowercase letters, and contains at least 2 unique letters.
+3. `target` is a lowercase letter.
+
+
+## 题目大意
+
+给定一个只包含小写字母的有序数组letters 和一个目标字母 target，寻找有序数组里面比目标字母大的最小字母。
+
+数组里字母的顺序是循环的。举个例子，如果目标字母target = 'z' 并且有序数组为 letters = ['a', 'b']，则答案返回 'a'。
+
+注:
+
+1. letters长度范围在[2, 10000]区间内。
+2. letters 仅由小写字母组成，最少包含两个不同的字母。
+3. 目标字母target 是一个小写字母。
+
+
+
+## 解题思路
+
+- 给出一个字节数组，在这个字节数组中查找在 target 后面的第一个字母。数组是环形的。
+- 这一题也是二分搜索的题目，先在数组里面查找 target，如果找到了，取这个字母的后一个字母。如果没有找到，就取 low 下标的那个字母。注意数组是环形的，所以最后结果需要对下标取余。