Merge branch 'youngyangyang04:master' into master

problems/0151.翻转字符串里的单词.md

@@ -639,7 +639,46 @@ func reverse(b []byte) {
     }
 }
 ```
-
+```go
+//双指针解法。指针逆序遍历，将遍历后得到的单词（间隔为空格，用以区分）顺序放置在额外空间
+//时间复杂度O(n)，空间复杂度O(n)
+func reverseWords(s string) string {
+    strBytes := []byte(s)
+    n := len(strBytes)
+    // 记录有效字符范围的起始和结束位置
+    start, end := 0, n-1
+    // 去除开头空格
+    for start < n && strBytes[start] == 32 {
+        start++
+    }
+    // 处理全是空格或空字符串情况
+    if start == n {
+        return ""
+    }
+    // 去除结尾空格
+    for end >= 0 && strBytes[end] == 32 {
+        end--
+    }
+    // 结果切片，预分配容量
+    res := make([]byte, 0, end-start+1)//这里挺重要的，本人之前没有预分配容量，每次循环都添加单词，导致内存超限（也可能就是我之前的思路有问题）
+    // 从后往前遍历有效字符范围
+    for i := end; i >= start; {
+        // 找单词起始位置，直接通过循环条件判断定位
+        for ; i >= start && strBytes[i] == 32; i-- {
+        }
+        j := i
+        for ; j >= start && strBytes[j]!= 32; j-- {
+        }
+        res = append(res, strBytes[j+1:i+1]...)
+        // 只在不是最后一个单词时添加空格
+        if j > start {
+            res = append(res, 32)
+        }
+        i = j
+    }
+    return string(res)
+}
+```
 
 
 ### JavaScript:

problems/0738.单调递增的数字.md

@@ -273,22 +273,20 @@ class Solution:
 ### Go 
 ```go
 func monotoneIncreasingDigits(n int) int {
-    s := strconv.Itoa(N)//将数字转为字符串，方便使用下标
-    ss := []byte(s)//将字符串转为byte数组，方便更改。
-    n := len(ss)
-    if n <= 1 {
-        return n
-    }
-    for i := n-1; i > 0; i-- {
-        if ss[i-1] > ss[i] {   //前一个大于后一位,前一位减1，后面的全部置为9
-            ss[i-1] -= 1
-            for j := i; j < n; j++ {   //后面的全部置为9
-                ss[j] = '9'
-            }
-        } 
-    }
-    res, _ := strconv.Atoi(string(ss))
-    return res 
+	s := strconv.Itoa(n)
+	// 从左到右遍历字符串，找到第一个不满足单调递增的位置
+	for i := len(s) - 2; i >= 0; i-- {
+		if s[i] > s[i+1] {
+			// 将该位置的数字减1
+			s = s[:i] + string(s[i]-1) + s[i+1:]
+			// 将该位置之后的所有数字置为9
+			for j := i + 1; j < len(s); j++ {
+				s = s[:j] + "9" + s[j+1:]
+			}
+		}
+	}
+	result, _ := strconv.Atoi(s)
+	return result
 }
 ```
 
@@ -447,3 +445,4 @@ public class Solution
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">
   <img src="../pics/网站星球宣传海报.jpg" width="1000"/>
 </a>
+

problems/kamacoder/0044.开发商购买土地.md

@@ -527,3 +527,89 @@ int main()
 }
 
 ```
+
+### Go
+
+前缀和
+
+```go
+package main
+
+import (
+    "fmt"
+    "os"
+    "bufio"
+    "strings"
+    "strconv"
+    "math"
+)
+    
+func main() {
+    var n, m int
+    
+    reader := bufio.NewReader(os.Stdin)
+    
+    line, _ := reader.ReadString('\n')
+    line = strings.TrimSpace(line)
+    params := strings.Split(line, " ")
+    
+    n, _ = strconv.Atoi(params[0])
+    m, _ = strconv.Atoi(params[1])//n和m读取完成
+    
+    land := make([][]int, n)//土地矩阵初始化
+    
+    for i := 0; i < n; i++ {
+        line, _ := reader.ReadString('\n')
+        line = strings.TrimSpace(line)
+        values := strings.Split(line, " ")
+        land[i] = make([]int, m)
+        for j := 0; j < m; j++ {
+            value, _ := strconv.Atoi(values[j])
+            land[i][j] = value
+        }
+    }//所有读取完成
+    
+    //初始化前缀和矩阵
+    preMatrix := make([][]int, n+1)
+	for i := 0; i <= n; i++ {
+		preMatrix[i] = make([]int, m+1)
+	}
+    
+    for a := 1; a < n+1; a++ {
+        for b := 1; b < m+1; b++ {
+            preMatrix[a][b] = land[a-1][b-1] + preMatrix[a-1][b] + preMatrix[a][b-1] - preMatrix[a-1][b-1]
+        }
+    }
+    
+    totalSum := preMatrix[n][m]
+    
+    minDiff := math.MaxInt32//初始化极大数，用于比较
+    
+    //按行分割
+    for i := 1; i < n; i++ {
+        topSum := preMatrix[i][m]
+        
+        bottomSum := totalSum - topSum
+        
+        diff := int(math.Abs(float64(topSum - bottomSum)))
+        if diff < minDiff {
+            minDiff = diff
+        }
+    }
+    
+    //按列分割
+    for j := 1; j < m; j++ {
+        topSum := preMatrix[n][j]
+        
+        bottomSum := totalSum - topSum
+        
+        diff := int(math.Abs(float64(topSum - bottomSum)))
+        if diff < minDiff {
+            minDiff = diff
+        }
+    }    
+    
+    fmt.Println(minDiff) 
+}
+```
+