add leetcode: offer-21-57-58

Author: CodeWater404

.gitignore

@@ -36,20 +36,22 @@ build/
 
 
 # Mobile Tools for Java (J2ME)
-  .mtj.tmp/
-  .logs/*
-  **/*.iml
-  # Package Files #
-  *.jar
-  **/*.jar
-  *.war
-  *.ear
-  target
-  .idea
-  .DS_Store
-  exports
-  # virtual machine crash logs, see                 
-  http://www.java.com/en/download/help/error_hotspot.xml
-  hs_err_pid*
-  .tags
-  .tags_sorted_by_file
+.mtj.tmp/
+.logs/*
+**/*.iml
+# Package Files #
+*.jar
+**/*.jar
+*.war
+*.ear
+target
+.idea
+.DS_Store
+exports
+# virtual machine crash logs, see                 
+http://www.java.com/en/download/help/error_hotspot.xml
+hs_err_pid*
+.tags
+.tags_sorted_by_file
+ 
+Algorithm/src/leetCode/subject/number1801_1850/test.java

Algorithm/src/offer/_21ReorderTheArraySoThatTheOddNumberPrecedesTheEvenNumber.java

@@ -0,0 +1,29 @@
+package offer;
+
+import org.junit.Test;
+
+/**
+ * @author ： CodeWater
+ * @create ：2022-07-05-16:23
+ * @Function Description ：21.调整数组顺序使奇数位于偶数前面
+ */
+public class _21ReorderTheArraySoThatTheOddNumberPrecedesTheEvenNumber {
+
+    @Test
+    public void exchange() {
+        int[] nums = {1,2,3,4};
+        int temp;
+        for (int i = 0, j = nums.length - 1; i < j; ) {
+            // 不加i<j，ij会越过去，导致可能刚交换的又变回原样。这里加了i<j之后，ij就是在相等的时候会退出
+            while (i < j && (nums[i] % 2 == 1)) i++;
+            while (i < j && (nums[j] % 2 == 0)) j--;
+
+            temp = nums[i];
+            nums[i] = nums[j];
+            nums[j] = temp;
+        }
+
+//        return nums;
+    }
+    
+}

Algorithm/src/offer/_57AndTwoNumbersOfS.java

@@ -0,0 +1,23 @@
+package offer;
+
+/**
+ * @author ： CodeWater
+ * @create ：2022-07-05-16:38
+ * @Function Description ：57. 和为s的两个数字
+ */
+public class _57AndTwoNumbersOfS {
+    class Solution {
+        public int[] twoSum(int[] nums, int target) {
+            for( int i = 0 , j = nums.length - 1 ; i < j ; ){
+                if( nums[i] + nums[j] > target ) j--;
+                else if( nums[i] + nums[j] < target ) i++;
+                else if( nums[i] + nums[j] == target ){
+                    return new int[]{ nums[i] , nums[j] };
+
+                }
+
+            }
+            return new int[0];
+        }
+    }
+}

Algorithm/src/offer/_58_1FlipWordOrder.java

@@ -0,0 +1,22 @@
+package offer;
+
+/**
+ * @author ： CodeWater
+ * @create ：2022-07-05-16:56
+ * @Function Description ：58.翻转单词顺序
+ */
+public class _58_1FlipWordOrder {
+    class Solution {
+        public String reverseWords(String s) {
+            // trim取出首尾的空格
+            String[] str = s.trim().split(" ");
+            StringBuilder res = new StringBuilder();
+            for( int i = str.length - 1 ; i >= 0 ; i-- ){
+                if(str[i].equals("")) continue;
+                res.append(str[i] + " " );
+
+            }
+            return res.toString().trim();
+        }
+    }
+}