848 finish

Author: aQua

Algorithms/0848.shifting-letters/README.md

@@ -0,0 +1,34 @@
+# [848. Shifting Letters](https://leetcode.com/problems/shifting-letters/)
+
+## 题目
+
+We have a string S of lowercase letters, and an integer array shifts.
+
+Call the shift of a letter, the next letter in the alphabet, (wrapping around so that 'z' becomes 'a').
+
+For example, shift('a') = 'b', shift('t') = 'u', and shift('z') = 'a'.
+
+Now for each shifts[i] = x, we want to shift the first i+1letters of S, x times.
+
+Return the final stringafter all such shifts to S are applied.
+
+Example 1:
+
+```text
+Input: S = "abc", shifts = [3,5,9]
+Output: "rpl"
+Explanation:
+We start with "abc".
+After shifting the first 1 letters of S by 3, we have "dbc".
+After shifting the first 2 letters of S by 5, we have "igc".
+After shifting the first 3 letters of S by 9, we have "rpl", the answer.
+```
+
+Note:
+
+1. 1 <= S.length = shifts.length <= 20000
+1. 0 <= shifts[i] <= 10 ^ 9
+
+## 解题思路
+
+见程序注释

Algorithms/0848.shifting-letters/shifting-letters.go

@@ -0,0 +1,29 @@
+package problem0848
+
+func shiftingLetters(S string, shifts []int) string {
+	size := len(S)
+	a := s2is(S)
+	shift := 0
+	for i := size - 1; 0 <= i; i-- {
+		shift += shifts[i]
+		shift %= 26
+		a[i] = (a[i] + shift) % 26
+	}
+	return is2s(a)
+}
+
+func s2is(s string) []int {
+	res := make([]int, len(s))
+	for i := range s {
+		res[i] = int(s[i] - 'a')
+	}
+	return res
+}
+
+func is2s(a []int) string {
+	bs := make([]byte, len(a))
+	for i, n := range a {
+		bs[i] = byte(n + 'a')
+	}
+	return string(bs)
+}

Algorithms/0848.shifting-letters/shifting-letters_test.go

@@ -0,0 +1,41 @@
+package problem0848
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+// tcs is testcase slice
+var tcs = []struct {
+	S      string
+	shifts []int
+	ans    string
+}{
+
+	{
+		"abc",
+		[]int{3, 5, 9},
+		"rpl",
+	},
+
+	// 可以有多个 testcase
+}
+
+func Test_shiftingLetters(t *testing.T) {
+	ast := assert.New(t)
+
+	for _, tc := range tcs {
+		fmt.Printf("~~%v~~\n", tc)
+		ast.Equal(tc.ans, shiftingLetters(tc.S, tc.shifts), "输入:%v", tc)
+	}
+}
+
+func Benchmark_shiftingLetters(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		for _, tc := range tcs {
+			shiftingLetters(tc.S, tc.shifts)
+		}
+	}
+}

leetcode.json

@@ -1,7 +1,7 @@
 {
 	"Username": "aQuaYi",
-	"Ranking": 1019,
-	"Updated": "2018-07-03T14:09:44.198054366+08:00",
+	"Ranking": 997,
+	"Updated": "2018-07-04T05:44:33.515334967+08:00",
 	"Record": {
 		"Easy": {
 			"Solved": 175,
@@ -1453,7 +1453,7 @@
 			"ID": 119,
 			"Title": "Pascal's Triangle II",
 			"TitleSlug": "pascals-triangle-ii",
-			"PassRate": "38%",
+			"PassRate": "39%",
 			"Difficulty": "Easy",
 			"IsAccepted": true,
 			"IsPaid": false,
@@ -4825,7 +4825,7 @@
 			"ID": 400,
 			"Title": "Nth Digit",
 			"TitleSlug": "nth-digit",
-			"PassRate": "30%",
+			"PassRate": "29%",
 			"Difficulty": "Easy",
 			"IsAccepted": true,
 			"IsPaid": false,
@@ -9865,7 +9865,7 @@
 			"ID": 820,
 			"Title": "Short Encoding of Words",
 			"TitleSlug": "short-encoding-of-words",
-			"PassRate": "42%",
+			"PassRate": "41%",
 			"Difficulty": "Medium",
 			"IsAccepted": true,
 			"IsPaid": false,
@@ -10033,7 +10033,7 @@
 			"ID": 834,
 			"Title": "Sum of Distances in Tree",
 			"TitleSlug": "sum-of-distances-in-tree",
-			"PassRate": "32%",
+			"PassRate": "31%",
 			"Difficulty": "Hard",
 			"IsAccepted": true,
 			"IsPaid": false,
@@ -10249,7 +10249,7 @@
 			"ID": 852,
 			"Title": "Peak Index in a Mountain Array",
 			"TitleSlug": "peak-index-in-a-mountain-array",
-			"PassRate": "68%",
+			"PassRate": "69%",
 			"Difficulty": "Easy",
 			"IsAccepted": false,
 			"IsPaid": false,
@@ -10369,7 +10369,7 @@
 			"ID": 862,
 			"Title": "Shortest Subarray with Sum at Least K",
 			"TitleSlug": "shortest-subarray-with-sum-at-least-k",
-			"PassRate": "14%",
+			"PassRate": "15%",
 			"Difficulty": "Hard",
 			"IsAccepted": false,
 			"IsPaid": false,
@@ -10393,7 +10393,7 @@
 			"ID": 864,
 			"Title": "Random Pick with Blacklist",
 			"TitleSlug": "random-pick-with-blacklist",
-			"PassRate": "0%",
+			"PassRate": "26%",
 			"Difficulty": "Hard",
 			"IsAccepted": false,
 			"IsPaid": false,