27. 移除元素

 public int removeElement(int[] nums, int val) {int res = 0;for (int i = 0; i < nums.length; i++) {if(nums[i]!=val){nums[res++] = nums[i];}}return res;}

26. 删除有序数组中的重复项

 class Solution {public int removeDuplicates(int[] nums) {int j = 0;for(int i=0;i<nums.length;i++){if(nums[i]!=nums[j]){nums[++j] = nums[i];}}return j+1;}}

80. 删除有序数组中的重复项 II

 class Solution {public int removeDuplicates(int[] nums) {int n = 2;int i = n,j=n;while(j<nums.length){if(nums[j]!=nums[i-n]){nums[i++] = nums[j];}j++;}return i;}}

11. 盛最多水的容器

 class Solution {public int maxArea(int[] height) {int l = 0,r = height.length-1;int res = 0;while(l<r){int t = Math.min(height[l],height[r]) * (r-l);res = Math.max(res,t);if(height[l]<=height[r]) {l++;}else{r--;}}return res;}}

189. 轮转数组

class Solution {public void rotate(int[] nums, int k) {int[] arr = new int[nums.length];for(int i=0;i<nums.length;i++){arr[(i+k)%nums.length] = nums[i];}for (int i = 0; i < nums.length; i++) {nums[i] = arr[i];}}}