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merged 2 commits into from
Dec 16, 2023
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feat: add solutions to lc problems: No.0896~0898 #2107

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37677f9
feat: add solutions to lc problems: No.0896~0898
yanglbme Dec 16, 2023
71c5a6b
fix: cpp code
yanglbme Dec 16, 2023
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113 changes: 47 additions & 66 deletions solution/0800-0899/0896.Monotonic Array/README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -57,7 +57,7 @@

否则遍历结束，说明是单调数组，返回 `true`。

时间复杂度 $O(n)$，空间复杂度 $O(1)$。其中 $n$ 为数组长度。
时间复杂度 $O(n)$，其中 $n$ 为数组长度。空间复杂度 $O(1)$。

<!-- tabs:start -->

Expand All @@ -68,23 +68,9 @@
```python
class Solution:
def isMonotonic(self, nums: List[int]) -> bool:
isIncr = isDecr = False
for i, v in enumerate(nums[1:]):
if v < nums[i]:
isIncr = True
elif v > nums[i]:
isDecr = True
if isIncr and isDecr:
return False
return True
```

```python
class Solution:
def isMonotonic(self, nums: List[int]) -> bool:
incr = all(a <= b for a, b in pairwise(nums))
decr = all(a >= b for a, b in pairwise(nums))
return incr or decr
asc = all(a <= b for a, b in pairwise(nums))
desc = all(a >= b for a, b in pairwise(nums))
return asc or desc
```

### **Java**
Expand All @@ -94,14 +80,14 @@ class Solution:
```java
class Solution {
public boolean isMonotonic(int[] nums) {
boolean isIncr = false, isDecr = false;
boolean asc = false, desc = false;
for (int i = 1; i < nums.length; ++i) {
if (nums[i] < nums[i - 1]) {
isIncr = true;
} else if (nums[i] > nums[i - 1]) {
isDecr = true;
if (nums[i - 1] < nums[i]) {
asc = true;
} else if (nums[i - 1] > nums[i]) {
desc = true;
}
if (isIncr && isDecr) {
if (asc && desc) {
return false;
}
}
Expand All @@ -116,12 +102,16 @@ class Solution {
class Solution {
public:
bool isMonotonic(vector<int>& nums) {
bool isIncr = false;
bool isDecr = false;
bool asc = false, desc = false;
for (int i = 1; i < nums.size(); ++i) {
if (nums[i] < nums[i - 1]) isIncr = true;
if (nums[i] > nums[i - 1]) isDecr = true;
if (isIncr && isDecr) return false;
if (nums[i - 1] < nums[i]) {
asc = true;
} else if (nums[i - 1] > nums[i]) {
desc = true;
}
if (asc && desc) {
return false;
}
}
return true;
}
Expand All @@ -132,14 +122,14 @@ public:

```go
func isMonotonic(nums []int) bool {
isIncr, isDecr := false, false
for i, v := range nums[1:] {
if v < nums[i] {
isIncr = true
} else if v > nums[i] {
isDecr = true
asc, desc := false, false
for i, x := range nums[1:] {
if nums[i] < x {
asc = true
} else if nums[i] > x {
desc = true
}
if isIncr && isDecr {
if asc && desc {
return false
}
}
Expand All @@ -155,16 +145,14 @@ func isMonotonic(nums []int) bool {
* @return {boolean}
*/
var isMonotonic = function (nums) {
let isIncr = false;
let isDecr = false;
let [asc, desc] = [false, false];
for (let i = 1; i < nums.length; ++i) {
if (nums[i] < nums[i - 1]) {
isIncr = true;
if (nums[i - 1] < nums[i]) {
asc = true;
} else if (nums[i - 1] > nums[i]) {
desc = true;
}
if (nums[i] > nums[i - 1]) {
isDecr = true;
}
if (isIncr && isDecr) {
if (asc && desc) {
return false;
}
}
Expand All @@ -176,18 +164,14 @@ var isMonotonic = function (nums) {

```ts
function isMonotonic(nums: number[]): boolean {
const n = nums.length;
let isOrder = false;
let isDecs = false;
for (let i = 1; i < n; i++) {
const pre = nums[i - 1];
const cur = nums[i];
if (pre < cur) {
isOrder = true;
} else if (pre > cur) {
isDecs = true;
let [asc, desc] = [false, false];
for (let i = 1; i < nums.length; ++i) {
if (nums[i - 1] < nums[i]) {
asc = true;
} else if (nums[i - 1] > nums[i]) {
desc = true;
}
if (isOrder && isDecs) {
if (asc && desc) {
return false;
}
}
Expand All @@ -200,18 +184,15 @@ function isMonotonic(nums: number[]): boolean {
```rust
impl Solution {
pub fn is_monotonic(nums: Vec<i32>) -> bool {
let n = nums.len();
let mut is_order = false;
let mut is_decs = false;
for i in 1..n {
let pre = nums[i - 1];
let cur = nums[i];
if pre < cur {
is_order = true;
} else if pre > cur {
is_decs = true;
let mut asc = false;
let mut desc = false;
for i in 1..nums.len() {
if nums[i - 1] < nums[i] {
asc = true;
} else if nums[i - 1] > nums[i] {
desc = true;
}
if is_order && is_decs {
if asc && desc {
return false;
}
}
Expand Down
119 changes: 54 additions & 65 deletions solution/0800-0899/0896.Monotonic Array/README_EN.md
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Original file line number Diff line number Diff line change
Expand Up @@ -42,45 +42,39 @@

## Solutions

**Solution 1: Single Traversal**

We traverse the array, and if an increasing or decreasing situation occurs, we record it. We then check whether both increasing and decreasing situations have occurred. If both have occurred, it means that the array is not monotonic, and we return `false`.

Otherwise, if we reach the end of the traversal, it means that the array is monotonic, and we return `true`.

The time complexity is $O(n)$, where $n$ is the length of the array. The space complexity is $O(1)$.

<!-- tabs:start -->

### **Python3**

```python
class Solution:
def isMonotonic(self, nums: List[int]) -> bool:
isIncr = isDecr = False
for i, v in enumerate(nums[1:]):
if v < nums[i]:
isIncr = True
elif v > nums[i]:
isDecr = True
if isIncr and isDecr:
return False
return True
```

```python
class Solution:
def isMonotonic(self, nums: List[int]) -> bool:
incr = all(a <= b for a, b in pairwise(nums))
decr = all(a >= b for a, b in pairwise(nums))
return incr or decr
asc = all(a <= b for a, b in pairwise(nums))
desc = all(a >= b for a, b in pairwise(nums))
return asc or desc
```

### **Java**

```java
class Solution {
public boolean isMonotonic(int[] nums) {
boolean isIncr = false, isDecr = false;
boolean asc = false, desc = false;
for (int i = 1; i < nums.length; ++i) {
if (nums[i] < nums[i - 1]) {
isIncr = true;
} else if (nums[i] > nums[i - 1]) {
isDecr = true;
if (nums[i - 1] < nums[i]) {
asc = true;
} else if (nums[i - 1] > nums[i]) {
desc = true;
}
if (isIncr && isDecr) {
if (asc && desc) {
return false;
}
}
Expand All @@ -95,12 +89,16 @@ class Solution {
class Solution {
public:
bool isMonotonic(vector<int>& nums) {
bool isIncr = false;
bool isDecr = false;
bool asc = false, desc = false;
for (int i = 1; i < nums.size(); ++i) {
if (nums[i] < nums[i - 1]) isIncr = true;
if (nums[i] > nums[i - 1]) isDecr = true;
if (isIncr && isDecr) return false;
if (nums[i - 1] < nums[i]) {
asc = true;
} else if (nums[i - 1] > nums[i]) {
desc = true;
}
if (asc && desc) {
return false;
}
}
return true;
}
Expand All @@ -111,14 +109,14 @@ public:

```go
func isMonotonic(nums []int) bool {
isIncr, isDecr := false, false
for i, v := range nums[1:] {
if v < nums[i] {
isIncr = true
} else if v > nums[i] {
isDecr = true
asc, desc := false, false
for i, x := range nums[1:] {
if nums[i] < x {
asc = true
} else if nums[i] > x {
desc = true
}
if isIncr && isDecr {
if asc && desc {
return false
}
}
Expand All @@ -134,16 +132,14 @@ func isMonotonic(nums []int) bool {
* @return {boolean}
*/
var isMonotonic = function (nums) {
let isIncr = false;
let isDecr = false;
let [asc, desc] = [false, false];
for (let i = 1; i < nums.length; ++i) {
if (nums[i] < nums[i - 1]) {
isIncr = true;
}
if (nums[i] > nums[i - 1]) {
isDecr = true;
if (nums[i - 1] < nums[i]) {
asc = true;
} else if (nums[i - 1] > nums[i]) {
desc = true;
}
if (isIncr && isDecr) {
if (asc && desc) {
return false;
}
}
Expand All @@ -155,18 +151,14 @@ var isMonotonic = function (nums) {

```ts
function isMonotonic(nums: number[]): boolean {
const n = nums.length;
let isOrder = false;
let isDecs = false;
for (let i = 1; i < n; i++) {
const pre = nums[i - 1];
const cur = nums[i];
if (pre < cur) {
isOrder = true;
} else if (pre > cur) {
isDecs = true;
let [asc, desc] = [false, false];
for (let i = 1; i < nums.length; ++i) {
if (nums[i - 1] < nums[i]) {
asc = true;
} else if (nums[i - 1] > nums[i]) {
desc = true;
}
if (isOrder && isDecs) {
if (asc && desc) {
return false;
}
}
Expand All @@ -179,18 +171,15 @@ function isMonotonic(nums: number[]): boolean {
```rust
impl Solution {
pub fn is_monotonic(nums: Vec<i32>) -> bool {
let n = nums.len();
let mut is_order = false;
let mut is_decs = false;
for i in 1..n {
let pre = nums[i - 1];
let cur = nums[i];
if pre < cur {
is_order = true;
} else if pre > cur {
is_decs = true;
let mut asc = false;
let mut desc = false;
for i in 1..nums.len() {
if nums[i - 1] < nums[i] {
asc = true;
} else if nums[i - 1] > nums[i] {
desc = true;
}
if is_order && is_decs {
if asc && desc {
return false;
}
}
Expand Down
14 changes: 9 additions & 5 deletions solution/0800-0899/0896.Monotonic Array/Solution.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -1,12 +1,16 @@
class Solution {
public:
bool isMonotonic(vector<int>& nums) {
bool isIncr = false;
bool isDecr = false;
bool asc = false, desc = false;
for (int i = 1; i < nums.size(); ++i) {
if (nums[i] < nums[i - 1]) isIncr = true;
if (nums[i] > nums[i - 1]) isDecr = true;
if (isIncr && isDecr) return false;
if (nums[i - 1] < nums[i]) {
asc = true;
} else if (nums[i - 1] > nums[i]) {
desc = true;
}
if (asc && desc) {
return false;
}
}
return true;
}
Expand Down
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