1. 合并有序数组

#include <iostream>
#include <vector>
using namespace std;class Solution {
public:void swap(int &a, int &b) {int temp = b;b = a;a = temp;}void merge(vector<int> &nums1, int m, vector<int> &nums2, int n) {int i , j;for (i = 0, j = 0; i < m && n > 0 && j < n; i++) {if (nums1[i] > nums2[j]) {int mi = m;while(mi > i){//s1[i] > s2[j] 全部往后移动一个,插入s2[j]nums1[mi] =  nums1[mi-1];mi--;}m = m+1;nums1[i] = nums2[j];j++;}}//s1 当前元素都小于 s2 把s2 补充进来while (j < n ) {nums1[i++] = nums2[j];j++;}}void merge2(vector<int> &nums1, int m, vector<int> &nums2, int n){int i = m+n-1;m--;n--;while(n >= 0){while(m>=0 && nums1[m] > nums2[n]){swap(nums1[i--],nums1[m--]);}swap(nums1[i--], nums2[n--]);}}void merge3(vector<int> &nums1, int m, vector<int> &nums2, int n){int i = m-1, j = n-1, s1 = m+n-1;while(s1 >= 0 && i >= 0 && j >= 0){if(nums1[i] > nums2[j]){nums1[s1] = nums1[i];i--;}else{nums1[s1] = nums2[j];j--;}s1--;}while(j >= 0 && s1 >= 0){nums1[s1] =  nums2[j];s1--;j--;}}
};int main() {vector<int> nums1 = {2,0};vector<int> nums2 = {1};int m = 1;int n = 1;Solution sol;sol.merge3(nums1, m, nums2, n);for (int i = 0; i < n + m; i++) {cout << nums1[i] << " ";}return 0;
}

2. 移除数组元素

class Solution {
public://笨方法时间有点长int removeElement(vector<int> &nums, int val) {for (vector<int>::iterator it = nums.begin(); it != nums.end();) {if (*it == val)nums.erase(it);elseit++;}return nums.size();}//左右指针解法int removeElement1(vector<int> &nums, int val) {int left = 0, right = 0;for (right = 0; right < nums.size(); right++) {if (nums[right] != val) {nums[left] = nums[right];left++;}}return left;}//左右指针优化int removeElement2(vector<int> &nums, int val) {int left = 0, right = nums.size();while (left < right) {if (nums[left] == val) {nums[left] = nums[right - 1];right--;} else {left++;}}return left;}
};