add offer47

Author: lily-lee

README.md

@@ -3,19 +3,20 @@
 
 
 ### Problems
-|            #            |                                                    Title                                                    |            Solution             | Difficulty |
-| :---------------------: | :---------------------------------------------------------------------------------------------------------: | :-----------------------------: | :--------: |
-| [1](./algorithms/0001)  |                          [1. 两数之和](https://leetcode-cn.com/problems/two-sum/)                           | [Go](./algorithms/0001/main.go) |    简单    |
-| [2](./algorithms/0002)  |                      [2. 两数相加](https://leetcode-cn.com/problems/add-two-numbers/)                       | [Go](./algorithms/0002/main.go) |    中等    |
-| [3](./algorithms/0003)  | [3. 无重复字符的最长子串](https://leetcode-cn.com/problems/longest-substring-without-repeating-characters/) | [Go](./algorithms/0003/main.go) |    中等    |
-| [4](./algorithms/0004)  |        [4. 寻找两个正序数组的中位数](https://leetcode-cn.com/problems/median-of-two-sorted-arrays/)         | [Go](./algorithms/0004/main.go) |    困难    |
-| [5](./algorithms/0005)  |             [5. 最长回文子串](https://leetcode-cn.com/problems/longest-palindromic-substring/)              | [Go](./algorithms/0005/main.go) |    中等    |
-| [7](./algorithms/0007)  |                      [7. 整数反转](https://leetcode-cn.com/problems/reverse-integer/)                       | [Go](./algorithms/0007/main.go) |    简单    |
-| [8](./algorithms/0008)  |            [8. 字符串转换整数 (atoi)](https://leetcode-cn.com/problems/string-to-integer-atoi/)             | [Go](./algorithms/0008/main.go) |    中等    |
-| [9](./algorithms/0009)  |                      [9. 回文数](https://leetcode-cn.com/problems/palindrome-number/)                       | [Go](./algorithms/0009/main.go) |    简单    |
-| [11](./algorithms/0011) |              [11. 盛最多水的容器](https://leetcode-cn.com/problems/container-with-most-water/)              | [Go](./algorithms/0011/main.go) |    中等    |
-| [14](./algorithms/0014) |                 [14. 最长公共前缀](https://leetcode-cn.com/problems/longest-common-prefix/)                 | [Go](./algorithms/0014/main.go) |    简单    |
-| [79](./algorithms/0079) |                        [79. 单词搜索](https://leetcode-cn.com/problems/word-search/)                        | [Go](./algorithms/0079/main.go) |    中等    |
+|                #                |                                                    Title                                                    |              Solution              | Difficulty |
+| :-----------------------------: | :---------------------------------------------------------------------------------------------------------: | :--------------------------------: | :--------: |
+|     [1](./algorithms/0001)      |                          [1. 两数之和](https://leetcode-cn.com/problems/two-sum/)                           |  [Go](./algorithms/0001/main.go)   |    简单    |
+|     [2](./algorithms/0002)      |                      [2. 两数相加](https://leetcode-cn.com/problems/add-two-numbers/)                       |  [Go](./algorithms/0002/main.go)   |    中等    |
+|     [3](./algorithms/0003)      | [3. 无重复字符的最长子串](https://leetcode-cn.com/problems/longest-substring-without-repeating-characters/) |  [Go](./algorithms/0003/main.go)   |    中等    |
+|     [4](./algorithms/0004)      |        [4. 寻找两个正序数组的中位数](https://leetcode-cn.com/problems/median-of-two-sorted-arrays/)         |  [Go](./algorithms/0004/main.go)   |    困难    |
+|     [5](./algorithms/0005)      |             [5. 最长回文子串](https://leetcode-cn.com/problems/longest-palindromic-substring/)              |  [Go](./algorithms/0005/main.go)   |    中等    |
+|     [7](./algorithms/0007)      |                      [7. 整数反转](https://leetcode-cn.com/problems/reverse-integer/)                       |  [Go](./algorithms/0007/main.go)   |    简单    |
+|     [8](./algorithms/0008)      |            [8. 字符串转换整数 (atoi)](https://leetcode-cn.com/problems/string-to-integer-atoi/)             |  [Go](./algorithms/0008/main.go)   |    中等    |
+|     [9](./algorithms/0009)      |                      [9. 回文数](https://leetcode-cn.com/problems/palindrome-number/)                       |  [Go](./algorithms/0009/main.go)   |    简单    |
+|     [11](./algorithms/0011)     |              [11. 盛最多水的容器](https://leetcode-cn.com/problems/container-with-most-water/)              |  [Go](./algorithms/0011/main.go)   |    中等    |
+|     [14](./algorithms/0014)     |                 [14. 最长公共前缀](https://leetcode-cn.com/problems/longest-common-prefix/)                 |  [Go](./algorithms/0014/main.go)   |    简单    |
+|     [79](./algorithms/0079)     |                        [79. 单词搜索](https://leetcode-cn.com/problems/word-search/)                        |  [Go](./algorithms/0079/main.go)   |    中等    |
+| [offer47](./algorithms/offer47) |       [剑指 Offer 47. 礼物的最大价值](https://leetcode-cn.com/problems/li-wu-de-zui-da-jie-zhi-lcof/)       | [Go](./algorithms/offer47/main.go) |    中等    |
 
 
 

algorithms/offer47/README.md

@@ -0,0 +1,27 @@
+#### [剑指 Offer 47. 礼物的最大价值](https://leetcode-cn.com/problems/li-wu-de-zui-da-jie-zhi-lcof/)
+
+难度中等
+
+在一个 m*n 的棋盘的每一格都放有一个礼物，每个礼物都有一定的价值（价值大于 0）。你可以从棋盘的左上角开始拿格子里的礼物，并每次向右或者向下移动一格、直到到达棋盘的右下角。给定一个棋盘及其上面的礼物的价值，请计算你最多能拿到多少价值的礼物？
+
+ 
+
+**示例 1:**
+
+```
+输入: 
+[
+  [1,3,1],
+  [1,5,1],
+  [4,2,1]
+]
+输出: 12
+解释: 路径 1→3→5→2→1 可以拿到最多价值的礼物
+```
+
+ 
+
+提示：
+
+- `0 < grid.length <= 200`
+- `0 < grid[0].length <= 200`

algorithms/offer47/main.go

@@ -0,0 +1,23 @@
+package offer47
+
+func maxValue(grid [][]int) int {
+	for i := 0; i < len(grid)-1; i++ {
+		grid[i+1][0] += grid[i][0]
+	}
+	for i := 0; i < len(grid[0])-1; i++ {
+		grid[0][i+1] += grid[0][i]
+	}
+	for m := 1; m < len(grid); m++ {
+		for n := 1; n < len(grid[0]); n++ {
+			grid[m][n] += max(grid[m][n-1], grid[m-1][n])
+		}
+	}
+	return grid[len(grid)-1][len(grid[0])-1]
+}
+
+func max(x, y int) int {
+	if x > y {
+		return x
+	}
+	return y
+}