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yanglbmeyanglbme
committedMar 22, 2023
feat: add solutions to lc problem: No.0665
No.0665.Non-decreasing Array
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Diff for: ‎solution/0600-0699/0665.Non-decreasing Array/README.md

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Original file line numberDiff line numberDiff line change
@@ -43,22 +43,123 @@
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<!-- 这里可写通用的实现逻辑 -->
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**方法一：两次遍历**
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在最多改变一个元素的情况下，若要将数组变成非递减数列，那么数组最多只能有一个位置，其左右两侧的元素不满足非递减数列的要求。也即数组中只会存在一个位置 $i$，使得 $nums[i] \gt nums[i+1]$。
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因此，我们可以从左到右遍历数组，找到第一个不满足非递减数列要求的位置 $i$，然后将 $nums[i]$ 修改为 $nums[i+1]$ 或者将 $nums[i+1]$ 修改为 $nums[i]$，再判断修改后的数组是否满足非递减数列的要求。如果满足，则返回 `true`，否则返回 `false`。
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遍历结束后，如果没有找到不满足非递减数列要求的位置，说明数组本身就是非递减数列，返回 `true`。
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时间复杂度 $O(n)$，空间复杂度 $O(1)$。其中 $n$ 为数组的长度。
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<!-- tabs:start -->
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### **Python3**
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<!-- 这里可写当前语言的特殊实现逻辑 -->
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```python
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class Solution:
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def checkPossibility(self, nums: List[int]) -> bool:
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def is_sorted(nums: List[int]) -> bool:
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return all(a <= b for a, b in pairwise(nums))
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n = len(nums)
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for i in range(n - 1):
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a, b = nums[i], nums[i + 1]
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if a > b:
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nums[i] = b
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if is_sorted(nums):
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return True
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nums[i] = nums[i + 1] = a
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return is_sorted(nums)
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return True
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```
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### **Java**
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<!-- 这里可写当前语言的特殊实现逻辑 -->
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```java
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class Solution {
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public boolean checkPossibility(int[] nums) {
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for (int i = 0; i < nums.length - 1; ++i) {
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int a = nums[i], b = nums[i + 1];
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if (a > b) {
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nums[i] = b;
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if (isSorted(nums)) {
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return true;
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}
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nums[i] = a;
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nums[i + 1] = a;
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return isSorted(nums);
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}
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}
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return true;
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}
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private boolean isSorted(int[] nums) {
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for (int i = 0; i < nums.length - 1; ++i) {
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if (nums[i] > nums[i + 1]) {
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return false;
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}
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}
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return true;
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}
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}
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```
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### **C++**
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```cpp
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class Solution {
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public:
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bool checkPossibility(vector<int>& nums) {
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int n = nums.size();
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for (int i = 0; i < n - 1; ++i) {
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int a = nums[i], b = nums[i + 1];
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if (a > b) {
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nums[i] = b;
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if (is_sorted(nums.begin(), nums.end())) {
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return true;
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}
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nums[i] = a;
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nums[i + 1] = a;
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return is_sorted(nums.begin(), nums.end());
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}
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}
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return true;
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}
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};
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```
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### **Go**
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```go
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func checkPossibility(nums []int) bool {
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isSorted := func(nums []int) bool {
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for i, b := range nums[1:] {
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if nums[i] > b {
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return false
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}
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}
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return true
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}
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for i := 0; i < len(nums)-1; i++ {
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a, b := nums[i], nums[i+1]
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if a > b {
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nums[i] = b
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if isSorted(nums) {
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return true
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}
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nums[i] = a
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nums[i+1] = a
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return isSorted(nums)
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}
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}
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return true
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}
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```
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### **...**

Diff for: ‎solution/0600-0699/0665.Non-decreasing Array/README_EN.md

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@@ -41,13 +41,104 @@
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### **Python3**
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```python
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class Solution:
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def checkPossibility(self, nums: List[int]) -> bool:
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def is_sorted(nums: List[int]) -> bool:
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return all(a <= b for a, b in pairwise(nums))
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n = len(nums)
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for i in range(n - 1):
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a, b = nums[i], nums[i + 1]
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if a > b:
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nums[i] = b
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if is_sorted(nums):
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return True
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nums[i] = nums[i + 1] = a
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return is_sorted(nums)
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return True
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```
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### **Java**
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```java
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class Solution {
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public boolean checkPossibility(int[] nums) {
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for (int i = 0; i < nums.length - 1; ++i) {
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int a = nums[i], b = nums[i + 1];
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if (a > b) {
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nums[i] = b;
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if (isSorted(nums)) {
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return true;
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}
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nums[i] = a;
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nums[i + 1] = a;
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return isSorted(nums);
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}
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}
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return true;
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}
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private boolean isSorted(int[] nums) {
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for (int i = 0; i < nums.length - 1; ++i) {
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if (nums[i] > nums[i + 1]) {
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return false;
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}
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}
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return true;
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}
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}
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```
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### **C++**
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```cpp
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class Solution {
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public:
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bool checkPossibility(vector<int>& nums) {
98+
int n = nums.size();
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for (int i = 0; i < n - 1; ++i) {
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int a = nums[i], b = nums[i + 1];
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if (a > b) {
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nums[i] = b;
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if (is_sorted(nums.begin(), nums.end())) {
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return true;
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}
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nums[i] = a;
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nums[i + 1] = a;
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return is_sorted(nums.begin(), nums.end());
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}
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}
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return true;
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}
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};
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```
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### **Go**
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```go
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func checkPossibility(nums []int) bool {
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isSorted := func(nums []int) bool {
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for i, b := range nums[1:] {
122+
if nums[i] > b {
123+
return false
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}
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}
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return true
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}
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for i := 0; i < len(nums)-1; i++ {
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a, b := nums[i], nums[i+1]
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if a > b {
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nums[i] = b
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if isSorted(nums) {
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return true
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}
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nums[i] = a
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nums[i+1] = a
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return isSorted(nums)
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}
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}
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return true
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}
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```
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### **...**

Diff for: ‎solution/0600-0699/0665.Non-decreasing Array/Solution.cpp

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,19 @@
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class Solution {
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public:
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bool checkPossibility(vector<int>& nums) {
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int n = nums.size();
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for (int i = 0; i < n - 1; ++i) {
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int a = nums[i], b = nums[i + 1];
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if (a > b) {
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nums[i] = b;
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if (is_sorted(nums.begin(), nums.end())) {
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return true;
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}
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nums[i] = a;
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nums[i + 1] = a;
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return is_sorted(nums.begin(), nums.end());
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}
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}
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return true;
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}
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};

Diff for: ‎solution/0600-0699/0665.Non-decreasing Array/Solution.go

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,23 @@
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func checkPossibility(nums []int) bool {
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isSorted := func(nums []int) bool {
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for i, b := range nums[1:] {
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if nums[i] > b {
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return false
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}
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}
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return true
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}
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for i := 0; i < len(nums)-1; i++ {
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a, b := nums[i], nums[i+1]
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if a > b {
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nums[i] = b
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if isSorted(nums) {
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return true
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}
17+
nums[i] = a
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nums[i+1] = a
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return isSorted(nums)
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}
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}
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return true
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}

Diff for: ‎solution/0600-0699/0665.Non-decreasing Array/Solution.java

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,26 @@
1+
class Solution {
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public boolean checkPossibility(int[] nums) {
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for (int i = 0; i < nums.length - 1; ++i) {
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int a = nums[i], b = nums[i + 1];
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if (a > b) {
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nums[i] = b;
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if (isSorted(nums)) {
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return true;
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}
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nums[i] = a;
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nums[i + 1] = a;
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return isSorted(nums);
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}
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}
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return true;
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}
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private boolean isSorted(int[] nums) {
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for (int i = 0; i < nums.length - 1; ++i) {
20+
if (nums[i] > nums[i + 1]) {
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return false;
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}
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}
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return true;
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}
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}

Diff for: ‎solution/0600-0699/0665.Non-decreasing Array/Solution.py

+13-21
Original file line numberDiff line numberDiff line change
@@ -1,23 +1,15 @@
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class Solution:
2-
def checkPossibility(self, nums):
3-
"""
4-
:type nums: List[int]
5-
:rtype: bool
6-
"""
7-
if len(nums) < 2:
8-
return True
9-
count = 0
10-
for i in range(1, len(nums)):
11-
if nums[i] < nums[i - 1]:
12-
if count == 1:
13-
return False
14-
if not (
15-
i + 1 == len(nums)
16-
or nums[i + 1] >= nums[i - 1]
17-
or i - 2 < 0
18-
or nums[i - 2] < nums[i]
19-
):
20-
return False
21-
else:
22-
count = 1
2+
def checkPossibility(self, nums: List[int]) -> bool:
3+
def is_sorted(nums: List[int]) -> bool:
4+
return all(a <= b for a, b in pairwise(nums))
5+
6+
n = len(nums)
7+
for i in range(n - 1):
8+
a, b = nums[i], nums[i + 1]
9+
if a > b:
10+
nums[i] = b
11+
if is_sorted(nums):
12+
return True
13+
nums[i] = nums[i + 1] = a
14+
return is_sorted(nums)
2315
return True

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