diff --git a/.gitignore b/.gitignore
index 86defc3c..eb72862a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,3 +2,4 @@
*.iml
.idea
out
+target
diff --git a/pom.xml b/pom.xml
new file mode 100644
index 00000000..5e02b9f3
--- /dev/null
+++ b/pom.xml
@@ -0,0 +1,83 @@
+
+
+ 4.0.0
+
+ com.blankkj
+ leetcode
+ 0.0.1-SNAPSHOT
+ pom
+
+
+ 1.8
+
+
+
+
+
+ log4j
+ log4j
+ 1.2.17
+
+
+ org.slf4j
+ slf4j-api
+ 1.7.21
+
+
+ org.slf4j
+ slf4j-log4j12
+ 1.7.21
+
+
+
+
+ junit
+ junit
+ 4.12
+ test
+
+
+
+
+
+
+
+
+
+
+
+
+ org.apache.maven.plugins
+ maven-compiler-plugin
+ 3.5.1
+
+
+ ${java.version}
+ ${java.version}
+
+
+
+ org.apache.maven.plugins
+ maven-dependency-plugin
+
+
+ copy-dependencies
+ prepare-package
+
+ copy-dependencies
+
+
+ provided
+ false
+ false
+ true
+ ./target/dependency
+
+
+
+
+
+
+
+
diff --git a/src/com/blankj/easy/_001/Solution.java b/src/com/blankj/easy/_001/Solution.java
index ff0af5f4..72c63825 100644
--- a/src/com/blankj/easy/_001/Solution.java
+++ b/src/com/blankj/easy/_001/Solution.java
@@ -35,6 +35,31 @@ public int[] twoSum(int[] nums, int target) {
return null;
}
+ // Input array is sorted
+ // https://leetcode.com/problems/two-sum-ii-input-array-is-sorted/description/
+ public int[] twoSumOrdered(int[] num, int target) {
+ int[] indice = new int[2];
+ if(num == null || num.length < 2) {
+ return indice;
+ }
+ int left = 0;
+ int right = num.length - 1;
+ while(left < right) {
+ int sum = num[left] + num[right];
+ if(sum == target) {
+ indice[0] = left;
+ indice[1] = right;
+ return indice;
+ } else if(sum < target) {
+ left++;
+ } else {
+ right--;
+ }
+
+ }
+ return indice;
+ }
+
public static void main(String[] args) {
Solution solution = new Solution();
int[] nums = new int[]{2, 7, 11, 15};
diff --git a/src/com/blankj/medium/_003/HashSetSolution.java b/src/com/blankj/medium/_003/HashSetSolution.java
new file mode 100644
index 00000000..b9139e56
--- /dev/null
+++ b/src/com/blankj/medium/_003/HashSetSolution.java
@@ -0,0 +1,39 @@
+package com.blankj.medium._003;
+
+import java.util.HashSet;
+import java.util.Set;
+
+/**
+ * Created by dash wang on 2/11/18.
+ *
+ * HashSet + 双指针 问题
+ */
+public class HashSetSolution {
+ public int lengthOfLongestSubstring(String s) {
+ int len = s.length();
+ Set set = new HashSet<>();
+ int max = 0;
+ int head = 0, tail = 0;
+ for (head = 0; head < len; head++) {
+ // 出现重复, 移动尾指针,直到不重复为止
+ while (set.contains(s.charAt(head))) {
+ set.remove(s.charAt(tail));
+ tail++;
+ }
+ set.add(s.charAt(head));
+ int tempLen = head - tail + 1;
+ if (tempLen > max) {
+ max = tempLen;
+ }
+ }
+ return max;
+ }
+
+ public static void main(String[] args) {
+ HashSetSolution solution = new HashSetSolution();
+ System.out.println(solution.lengthOfLongestSubstring("abcabcbb"));
+ System.out.println(solution.lengthOfLongestSubstring("bbbbb"));
+ System.out.println(solution.lengthOfLongestSubstring("pwwkew"));
+ System.out.println(solution.lengthOfLongestSubstring("Abcabcbb"));
+ }
+}
diff --git a/src/com/blankj/medium/_015/Solution.java b/src/com/blankj/medium/_015/Solution.java
index b4af0e08..0860ac83 100644
--- a/src/com/blankj/medium/_015/Solution.java
+++ b/src/com/blankj/medium/_015/Solution.java
@@ -10,6 +10,9 @@
* blog : http://blankj.com
* time : 2017/10/14
* desc :
+ * 题意是让你从数组中找出所有三个和为 0 的元素构成的非重复序列，这样的话我们可以把数组先做下排序，
+ * 然后遍历这个排序数组，用两个指针分别指向当前元素的下一个和数组尾部，判断三者的和与 0 的大小来移动两个指针，
+ * 其中细节操作就是优化和去重。
*
*/
public class Solution {
@@ -17,20 +20,25 @@ public List> threeSum(int[] nums) {
List> list = new ArrayList<>();
int len = nums.length;
if (len < 3) return list;
+ // 先排序
Arrays.sort(nums);
int max = nums[len - 1];
+ // 最大值小于0, 那么不存在sum == 0 的解
if (max < 0) return list;
for (int i = 0; i < len - 2; ) {
+ // 最小值小于0, 那么不存在sum == 0 的解
if (nums[i] > 0) break;
if (nums[i] + 2 * max < 0) {
while (nums[i] == nums[++i] && i < len - 2) ;
continue;
}
+ // 对于任意一个nums[i]，在数组中的其他数中解2sum问题，目标为target-sums[i]
int left = i + 1, right = len - 1;
while (left < right) {
int sum = nums[i] + nums[left] + nums[right];
if (sum == 0) {
list.add(Arrays.asList(nums[i], nums[left], nums[right]));
+ // 去重
while (nums[left] == nums[++left] && left < right) ;
while (nums[right] == nums[--right] && left < right) ;
} else if (sum < 0) ++left;
diff --git a/src/com/blankj/medium/_033/Solution2.java b/src/com/blankj/medium/_033/Solution2.java
new file mode 100644
index 00000000..ee0d472e
--- /dev/null
+++ b/src/com/blankj/medium/_033/Solution2.java
@@ -0,0 +1,65 @@
+package com.blankj.medium._033;
+
+/**
+ * Created by dash wang on 2/11/18.
+ */
+public class Solution2 {
+
+ private int findDivisionIndex(int[] nums, int len) {
+ int left = 0, right = 1;
+ while (right < len && nums[left] < nums[right]) {
+ left++;
+ right++;
+ }
+ return left;
+ }
+
+ private int binarySearchRecursive(int[] nums, int low, int high, int target) {
+ int foundIndex = -1;
+ while (low < high) {
+ int mid = (low + high) / 2;
+ if (nums[mid] == target) {
+ return mid;
+ } else if (nums[mid] > target) {
+ return binarySearchRecursive(nums, low, mid - 1, target);
+ } else {
+ return binarySearchRecursive(nums, mid + 1, high, target);
+ }
+ }
+ return foundIndex;
+ }
+
+ private int binarySearchIteration(int[] nums, int low, int high, int target) {
+ int foundIndex = -1;
+ while(low < high) {
+ int mid = (low + high) / 2;
+ if(nums[mid] == target) {
+ return mid;
+ } else if(nums[mid] > target) {
+ high = mid - 1;
+ } else {
+ low = mid + 1;
+ }
+ }
+ return foundIndex;
+ }
+
+ public int search(int[] nums, int target) {
+ int index = -1;
+ int len = nums.length;
+ // Find division index
+ int divisionIndex = findDivisionIndex(nums, len);
+ // Decide which side to search
+ if (nums[0] <= target && nums[divisionIndex] >= target) {
+ index = binarySearchIteration(nums, 0, divisionIndex, target);
+ } else if (nums[divisionIndex + 1] <= target && nums[len - 1] >= target) {
+ index = binarySearchIteration(nums, divisionIndex + 1, len, target);
+ }
+ return index;
+ }
+
+ public static void main(String[] args) {
+ Solution2 solution2 = new Solution2();
+ System.out.println(solution2.search(new int[]{2, 1}, 1));
+ }
+}