--

src/main/java/cn/whaifree/leetCode/String/LeetCode151.java

@@ -2,10 +2,7 @@ package cn.whaifree.leetCode.String;
 
 import org.junit.Test;
 
-import java.util.ArrayList;
+import java.util.*;
-import java.util.Arrays;
-import java.util.LinkedList;
-import java.util.List;
 
 
 public class LeetCode151 {
@@ -15,7 +12,7 @@ public class LeetCode151 {
     @Test
     public void test() {
         String s = "  a b cd ef g  ";
-        System.out.println(new Solution1().reverseWords(s));
+        System.out.println(new Solution2().reverseWords(s));
 
 
     }
@@ -109,4 +106,18 @@ public class LeetCode151 {
 
     }
 
+
+    class Solution2{
+
+        public String reverseWords(String s) {
+            // 删除前后空白
+            String trim = s.trim();
+            String[] split = trim.split("\\s+");
+            List<String> list = Arrays.asList(split);
+            Collections.reverse(list);
+            return String.join(" ", list);
+        }
+
+    }
+
 }

src/main/java/cn/whaifree/redo/LeetCode151.java

@@ -0,0 +1,71 @@
+package cn.whaifree.redo;
+
+import org.junit.Test;
+
+public class LeetCode151 {
+
+    @Test
+    public void test() {
+        Solution solution = new Solution();
+        String s = solution.reverseWords(" abc    def  ");
+
+        System.out.println(s);
+    }
+
+    class Solution {
+        public String reverseWords(String s) {
+
+            // 去除空格
+            StringBuilder stringBuilder = removeExtraSpace(s);
+            // 逆转
+            reverse(stringBuilder, 0, stringBuilder.length() - 1);
+            // 对单词逆转
+            reverseWord(stringBuilder);
+            return stringBuilder.toString();
+        }
+
+
+        public StringBuilder removeExtraSpace(String s) {
+            int left = 0;
+            int right = s.length() - 1;
+            while (s.charAt(left)==' ') left++;
+            while (s.charAt(right)==' ') right--;
+
+            StringBuilder stringBuilder = new StringBuilder();
+            while (left <= right) {
+                if (s.charAt(left) != ' ' || s.charAt(left + 1) != ' ') {
+                    stringBuilder.append(s.charAt(left));
+                }
+                left++;
+            }
+            return stringBuilder;
+        }
+
+        public void reverse(StringBuilder s, int left, int right) {
+            while (left < right) {
+                char tmp = s.charAt(left);
+                s.setCharAt(left, s.charAt(right));
+                s.setCharAt(right, tmp);
+                left++;
+                right--;
+            }
+
+        }
+
+
+        public void reverseWord(StringBuilder s) {
+
+            int left = 0;
+            int right = 0;
+            while (right <= s.length()) {
+                if (right == s.length() - 1 || s.charAt(right + 1) == ' ') {
+                    reverse(s, left, right);
+                    left = right++ + 2;
+                }
+                right++;
+            }
+
+
+        }
+    }
+}

src/main/java/cn/whaifree/redo/LeetCode18.java

@@ -0,0 +1,74 @@
+package cn.whaifree.redo;
+
+import org.junit.Test;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+public class LeetCode18 {
+
+    @Test
+    public void test() {
+//        System.out.println(new Solution().fourSum(new int[]{1, 0, -1, 0, -2, 2}, 0));
+        int[] nums = new int[]{-3,-2,-1,0,0,1,2,3};
+        // [-3,0,1,2]
+        System.out.println(new Solution().fourSum(nums, 0));
+    }
+
+    // 四个数之和
+    class Solution {
+        public List<List<Integer>> fourSum(int[] nums, int target) {
+
+            Arrays.sort(nums);
+            List<List<Integer>> lists = new ArrayList<>();
+
+            if (nums[0] > target && nums[0] > 0) {
+                return lists;
+            }
+
+            for (int i = 0; i < nums.length; i++) {
+
+                // 第一次给过
+                if (i > 0 && nums[i] == nums[i - 1]) {
+                    continue;
+                }
+
+
+                for (int j = i + 1; j < nums.length; j++) {
+
+                    // 第一次给过
+                    if (j > i + 1 && nums[j] == nums[j - 1]) {
+                        continue;
+                    }
+
+                    int rignt = nums.length - 1;
+                    int left = j + 1;
+                    while (left < rignt) {
+                        int sum = nums[i] + nums[j] + nums[left] + nums[rignt];
+                        if (sum > target) {
+                            rignt--;
+                        } else if (sum < target) {
+                            left++;
+                        } else {
+                            lists.add(Arrays.asList(nums[i], nums[j], nums[left], nums[rignt]));
+
+                            while (left < rignt && nums[left + 1] == nums[left]) left++;
+                            // 注意这里 right-1
+                            while (left < rignt && nums[rignt - 1] == nums[rignt]) rignt--;
+
+                            left++;
+                            rignt--;
+
+                        }
+
+                    }
+
+
+                }
+
+            }
+            return lists;
+        }
+    }
+}

src/main/java/cn/whaifree/redo/LeetCode209.java

@@ -0,0 +1,40 @@
+package cn.whaifree.redo;
+
+import org.junit.Test;
+
+public class LeetCode209 {
+
+    @Test
+    public void test() {
+        System.out.println(new Solution().minSubArrayLen(7, new int[]{2,3,1,2,4,3}));
+    }
+
+    class Solution {
+        public int minSubArrayLen(int target, int[] nums) {
+
+
+            int left = 0;
+            int right = 0;
+            int min = Integer.MAX_VALUE;
+            int sum = 0;
+
+            while (right < nums.length) {
+                sum += nums[right];
+
+                while (sum >= target){
+                    // sum内删除left
+                    sum -= nums[left];
+                    min = Math.min(min, right - left + 1);
+                    left++;
+                }
+                right++;
+            }
+
+
+
+            return min == Integer.MAX_VALUE ? 0 : min;
+        }
+
+
+    }
+}

src/main/java/cn/whaifree/redo/LeetCode28.java

@@ -0,0 +1,31 @@
+package cn.whaifree.redo;
+
+import org.junit.Test;
+
+public class LeetCode28 {
+
+    @Test
+    public void test() {
+        System.out.println(new Solution().strStr("hello", "h"));
+    }
+
+    class Solution {
+        public int strStr(String haystack, String needle) {
+
+
+            int begin = 0;
+            int end = begin + needle.length();
+            while (end <= haystack.length()) {
+                if (haystack.substring(begin, end).equals(needle)) {
+                    return begin;
+                }
+                begin++;
+                end++;
+            }
+
+
+
+            return -1;
+        }
+    }
+}