Skip to content

Navigation Menu

Sign in
Appearance settings

Search code, repositories, users, issues, pull requests...

Provide feedback

We read every piece of feedback, and take your input very seriously.

Saved searches

Use saved searches to filter your results more quickly
Sign up
Appearance settings

Commit ca80e6d

Browse files
feat: add solutions to lc problems: No.2908,2909 (#1864)
1 parent e008b9f commit ca80e6d

File tree

14 files changed

+614
-12
lines changed

14 files changed

+614
-12
lines changed

‎solution/2900-2999/2908.Minimum Sum of Mountain Triplets I/README.md‎

Lines changed: 107 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -62,34 +62,138 @@
6262

6363
<!-- 这里可写通用的实现逻辑 -->
6464

65+
**方法一:预处理 + 枚举**
66+
67+
我们可以预处理出每个位置右侧的最小值,记录在数组 $right[i]$ 中,即 $right[i]$ 表示 $nums[i+1..n-1]$ 中的最小值。
68+
69+
接下来,我们从左到右枚举山形三元组的中间元素 $nums[i],ドル用一个变量 $left$ 表示 $nums[0..i-1]$ 中的最小值,用一个变量 $ans$ 表示当前找到的最小元素和。对于每个 $i,ドル我们需要找到满足 $left < nums[i]$ 且 $right[i+1] < nums[i]$ 的元素 $nums[i],ドル并更新 $ans$。
70+
71+
最后,如果 $ans$ 仍然为初始值,则说明不存在山形三元组,返回 $-1$。
72+
73+
时间复杂度 $O(n),ドル空间复杂度 $O(n)$。其中 $n$ 为数组长度。
74+
6575
<!-- tabs:start -->
6676

6777
### **Python3**
6878

6979
<!-- 这里可写当前语言的特殊实现逻辑 -->
7080

7181
```python
72-
82+
class Solution:
83+
def minimumSum(self, nums: List[int]) -> int:
84+
n = len(nums)
85+
right = [inf] * (n + 1)
86+
for i in range(n - 1, -1, -1):
87+
right[i] = min(right[i + 1], nums[i])
88+
ans = left = inf
89+
for i, x in enumerate(nums):
90+
if left < x and right[i + 1] < x:
91+
ans = min(ans, left + x + right[i + 1])
92+
left = min(left, x)
93+
return -1 if ans == inf else ans
7394
```
7495

7596
### **Java**
7697

7798
<!-- 这里可写当前语言的特殊实现逻辑 -->
7899

79100
```java
80-
101+
class Solution {
102+
public int minimumSum(int[] nums) {
103+
int n = nums.length;
104+
int[] right = new int[n + 1];
105+
final int inf = 1 << 30;
106+
right[n] = inf;
107+
for (int i = n - 1; i >= 0; --i) {
108+
right[i] = Math.min(right[i + 1], nums[i]);
109+
}
110+
int ans = inf, left = inf;
111+
for (int i = 0; i < n; ++i) {
112+
if (left < nums[i] && right[i + 1] < nums[i]) {
113+
ans = Math.min(ans, left + nums[i] + right[i + 1]);
114+
}
115+
left = Math.min(left, nums[i]);
116+
}
117+
return ans == inf ? -1 : ans;
118+
}
119+
}
81120
```
82121

83122
### **C++**
84123

85124
```cpp
86-
125+
class Solution {
126+
public:
127+
int minimumSum(vector<int>& nums) {
128+
int n = nums.size();
129+
const int inf = 1 << 30;
130+
int right[n + 1];
131+
right[n] = inf;
132+
for (int i = n - 1; ~i; --i) {
133+
right[i] = min(right[i + 1], nums[i]);
134+
}
135+
int ans = inf, left = inf;
136+
for (int i = 0; i < n; ++i) {
137+
if (left < nums[i] && right[i + 1] < nums[i]) {
138+
ans = min(ans, left + nums[i] + right[i + 1]);
139+
}
140+
left = min(left, nums[i]);
141+
}
142+
return ans == inf ? -1 : ans;
143+
}
144+
};
87145
```
88146
89147
### **Go**
90148
91149
```go
150+
func minimumSum(nums []int) int {
151+
n := len(nums)
152+
const inf = 1 << 30
153+
right := make([]int, n+1)
154+
right[n] = inf
155+
for i := n - 1; i >= 0; i-- {
156+
right[i] = min(right[i+1], nums[i])
157+
}
158+
ans, left := inf, inf
159+
for i, x := range nums {
160+
if left < x && right[i+1] < x {
161+
ans = min(ans, left+x+right[i+1])
162+
}
163+
left = min(left, x)
164+
}
165+
if ans == inf {
166+
return -1
167+
}
168+
return ans
169+
}
170+
171+
func min(a, b int) int {
172+
if a < b {
173+
return a
174+
}
175+
return b
176+
}
177+
```
92178

179+
### **TypeScript**
180+
181+
```ts
182+
function minimumSum(nums: number[]): number {
183+
const n = nums.length;
184+
const right: number[] = Array(n + 1).fill(Infinity);
185+
for (let i = n - 1; ~i; --i) {
186+
right[i] = Math.min(right[i + 1], nums[i]);
187+
}
188+
let [ans, left] = [Infinity, Infinity];
189+
for (let i = 0; i < n; ++i) {
190+
if (left < nums[i] && right[i + 1] < nums[i]) {
191+
ans = Math.min(ans, left + nums[i] + right[i + 1]);
192+
}
193+
left = Math.min(left, nums[i]);
194+
}
195+
return ans === Infinity ? -1 : ans;
196+
}
93197
```
94198

95199
### **...**

‎solution/2900-2999/2908.Minimum Sum of Mountain Triplets I/README_EN.md‎

Lines changed: 107 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -56,30 +56,134 @@ And the sum of this triplet is nums[1] + nums[3] + nums[5] = 13. It can be shown
5656

5757
## Solutions
5858

59+
**Solution 1: Preprocessing + Enumeration**
60+
61+
We can preprocess the minimum value on the right side of each position and record it in the array $right[i],ドル where $right[i]$ represents the minimum value in $nums[i+1..n-1]$.
62+
63+
Next, we enumerate the middle element $nums[i]$ of the mountain triplet from left to right, and use a variable $left$ to represent the minimum value in $ums[0..i-1],ドル and a variable $ans$ to represent the current minimum element sum found. For each $i,ドル we need to find the element $nums[i]$ that satisfies $left < nums[i]$ and $right[i+1] < nums[i],ドル and update $ans$.
64+
65+
Finally, if $ans$ is still the initial value, it means that there is no mountain triplet, and we return $-1$.
66+
67+
The time complexity is $O(n),ドル and the space complexity is $O(n)$. Here, $n$ is the length of the array.
68+
5969
<!-- tabs:start -->
6070

6171
### **Python3**
6272

6373
```python
64-
74+
class Solution:
75+
def minimumSum(self, nums: List[int]) -> int:
76+
n = len(nums)
77+
right = [inf] * (n + 1)
78+
for i in range(n - 1, -1, -1):
79+
right[i] = min(right[i + 1], nums[i])
80+
ans = left = inf
81+
for i, x in enumerate(nums):
82+
if left < x and right[i + 1] < x:
83+
ans = min(ans, left + x + right[i + 1])
84+
left = min(left, x)
85+
return -1 if ans == inf else ans
6586
```
6687

6788
### **Java**
6889

6990
```java
70-
91+
class Solution {
92+
public int minimumSum(int[] nums) {
93+
int n = nums.length;
94+
int[] right = new int[n + 1];
95+
final int inf = 1 << 30;
96+
right[n] = inf;
97+
for (int i = n - 1; i >= 0; --i) {
98+
right[i] = Math.min(right[i + 1], nums[i]);
99+
}
100+
int ans = inf, left = inf;
101+
for (int i = 0; i < n; ++i) {
102+
if (left < nums[i] && right[i + 1] < nums[i]) {
103+
ans = Math.min(ans, left + nums[i] + right[i + 1]);
104+
}
105+
left = Math.min(left, nums[i]);
106+
}
107+
return ans == inf ? -1 : ans;
108+
}
109+
}
71110
```
72111

73112
### **C++**
74113

75114
```cpp
76-
115+
class Solution {
116+
public:
117+
int minimumSum(vector<int>& nums) {
118+
int n = nums.size();
119+
const int inf = 1 << 30;
120+
int right[n + 1];
121+
right[n] = inf;
122+
for (int i = n - 1; ~i; --i) {
123+
right[i] = min(right[i + 1], nums[i]);
124+
}
125+
int ans = inf, left = inf;
126+
for (int i = 0; i < n; ++i) {
127+
if (left < nums[i] && right[i + 1] < nums[i]) {
128+
ans = min(ans, left + nums[i] + right[i + 1]);
129+
}
130+
left = min(left, nums[i]);
131+
}
132+
return ans == inf ? -1 : ans;
133+
}
134+
};
77135
```
78136
79137
### **Go**
80138
81139
```go
140+
func minimumSum(nums []int) int {
141+
n := len(nums)
142+
const inf = 1 << 30
143+
right := make([]int, n+1)
144+
right[n] = inf
145+
for i := n - 1; i >= 0; i-- {
146+
right[i] = min(right[i+1], nums[i])
147+
}
148+
ans, left := inf, inf
149+
for i, x := range nums {
150+
if left < x && right[i+1] < x {
151+
ans = min(ans, left+x+right[i+1])
152+
}
153+
left = min(left, x)
154+
}
155+
if ans == inf {
156+
return -1
157+
}
158+
return ans
159+
}
160+
161+
func min(a, b int) int {
162+
if a < b {
163+
return a
164+
}
165+
return b
166+
}
167+
```
82168

169+
### **TypeScript**
170+
171+
```ts
172+
function minimumSum(nums: number[]): number {
173+
const n = nums.length;
174+
const right: number[] = Array(n + 1).fill(Infinity);
175+
for (let i = n - 1; ~i; --i) {
176+
right[i] = Math.min(right[i + 1], nums[i]);
177+
}
178+
let [ans, left] = [Infinity, Infinity];
179+
for (let i = 0; i < n; ++i) {
180+
if (left < nums[i] && right[i + 1] < nums[i]) {
181+
ans = Math.min(ans, left + nums[i] + right[i + 1]);
182+
}
183+
left = Math.min(left, nums[i]);
184+
}
185+
return ans === Infinity ? -1 : ans;
186+
}
83187
```
84188

85189
### **...**
Lines changed: 20 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,20 @@
1+
class Solution {
2+
public:
3+
int minimumSum(vector<int>& nums) {
4+
int n = nums.size();
5+
const int inf = 1 << 30;
6+
int right[n + 1];
7+
right[n] = inf;
8+
for (int i = n - 1; ~i; --i) {
9+
right[i] = min(right[i + 1], nums[i]);
10+
}
11+
int ans = inf, left = inf;
12+
for (int i = 0; i < n; ++i) {
13+
if (left < nums[i] && right[i + 1] < nums[i]) {
14+
ans = min(ans, left + nums[i] + right[i + 1]);
15+
}
16+
left = min(left, nums[i]);
17+
}
18+
return ans == inf ? -1 : ans;
19+
}
20+
};
Lines changed: 27 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,27 @@
1+
func minimumSum(nums []int) int {
2+
n := len(nums)
3+
const inf = 1 << 30
4+
right := make([]int, n+1)
5+
right[n] = inf
6+
for i := n - 1; i >= 0; i-- {
7+
right[i] = min(right[i+1], nums[i])
8+
}
9+
ans, left := inf, inf
10+
for i, x := range nums {
11+
if left < x && right[i+1] < x {
12+
ans = min(ans, left+x+right[i+1])
13+
}
14+
left = min(left, x)
15+
}
16+
if ans == inf {
17+
return -1
18+
}
19+
return ans
20+
}
21+
22+
func min(a, b int) int {
23+
if a < b {
24+
return a
25+
}
26+
return b
27+
}
Lines changed: 19 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,19 @@
1+
class Solution {
2+
public int minimumSum(int[] nums) {
3+
int n = nums.length;
4+
int[] right = new int[n + 1];
5+
final int inf = 1 << 30;
6+
right[n] = inf;
7+
for (int i = n - 1; i >= 0; --i) {
8+
right[i] = Math.min(right[i + 1], nums[i]);
9+
}
10+
int ans = inf, left = inf;
11+
for (int i = 0; i < n; ++i) {
12+
if (left < nums[i] && right[i + 1] < nums[i]) {
13+
ans = Math.min(ans, left + nums[i] + right[i + 1]);
14+
}
15+
left = Math.min(left, nums[i]);
16+
}
17+
return ans == inf ? -1 : ans;
18+
}
19+
}
Lines changed: 12 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,12 @@
1+
class Solution:
2+
def minimumSum(self, nums: List[int]) -> int:
3+
n = len(nums)
4+
right = [inf] * (n + 1)
5+
for i in range(n - 1, -1, -1):
6+
right[i] = min(right[i + 1], nums[i])
7+
ans = left = inf
8+
for i, x in enumerate(nums):
9+
if left < x and right[i + 1] < x:
10+
ans = min(ans, left + x + right[i + 1])
11+
left = min(left, x)
12+
return -1 if ans == inf else ans
Lines changed: 15 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,15 @@
1+
function minimumSum(nums: number[]): number {
2+
const n = nums.length;
3+
const right: number[] = Array(n + 1).fill(Infinity);
4+
for (let i = n - 1; ~i; --i) {
5+
right[i] = Math.min(right[i + 1], nums[i]);
6+
}
7+
let [ans, left] = [Infinity, Infinity];
8+
for (let i = 0; i < n; ++i) {
9+
if (left < nums[i] && right[i + 1] < nums[i]) {
10+
ans = Math.min(ans, left + nums[i] + right[i + 1]);
11+
}
12+
left = Math.min(left, nums[i]);
13+
}
14+
return ans === Infinity ? -1 : ans;
15+
}

0 commit comments

Comments
(0)

AltStyle によって変換されたページ (->オリジナル) /