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 a6b0106

Browse files
committed
feat: add solutions to lc problems: No.0084,0085
* No.0084.Largest Rectangle in Histogram/ * No.0085.Maximal Rectangle
1 parent a430d33 commit a6b0106

File tree

9 files changed

+538
-36
lines changed

9 files changed

+538
-36
lines changed

‎solution/0000-0099/0084.Largest Rectangle in Histogram/README.md‎

Lines changed: 29 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -43,7 +43,7 @@
4343

4444
<!-- 这里可写通用的实现逻辑 -->
4545

46-
单调栈。
46+
**方法一:单调栈**
4747

4848
单调栈常见模型:找出每个数左/右边**离它最近的**且**比它大/小的数**。模板:
4949

@@ -55,7 +55,9 @@ for i in range(n):
5555
stk.append(i)
5656
```
5757

58-
枚举每根柱子的高度 h 作为矩形的高度,向左右两边找第一个高度小于 h 的下标 `left[i]`, `right[i]`。那么此时矩形面积为 `h * (right[i] - left[i] - 1)`,求最大值即可。
58+
枚举每根柱子的高度 $h$ 作为矩形的高度,向左右两边找第一个高度小于 $h$ 的下标 $left_i,ドル $right_i$。那么此时矩形面积为 $h \times (right_i-left_i-1),ドル求最大值即可。
59+
60+
时间复杂度 $O(n),ドル其中 $n$ 表示 $heights$ 的长度。
5961

6062
<!-- tabs:start -->
6163

@@ -66,7 +68,7 @@ for i in range(n):
6668
```python
6769
class Solution:
6870
def largestRectangleArea(self, heights: List[int]) -> int:
69-
res, n =0, len(heights)
71+
n = len(heights)
7072
stk = []
7173
left = [-1] * n
7274
right = [n] * n
@@ -77,9 +79,31 @@ class Solution:
7779
if stk:
7880
left[i] = stk[-1]
7981
stk.append(i)
82+
return max(h * (right[i] - left[i] - 1) for i, h in enumerate(heights))
83+
```
84+
85+
```python
86+
class Solution:
87+
def largestRectangleArea(self, heights: List[int]) -> int:
88+
n = len(heights)
89+
stk = []
90+
left = [-1] * n
91+
right = [n] * n
8092
for i, h in enumerate(heights):
81-
res = max(res, h * (right[i] - left[i] - 1))
82-
return res
93+
while stk and heights[stk[-1]] >= h:
94+
stk.pop()
95+
if stk:
96+
left[i] = stk[-1]
97+
stk.append(i)
98+
stk = []
99+
for i in range(n - 1, -1, -1):
100+
h = heights[i]
101+
while stk and heights[stk[-1]] >= h:
102+
stk.pop()
103+
if stk:
104+
right[i] = stk[-1]
105+
stk.append(i)
106+
return max(h * (right[i] - left[i] - 1) for i, h in enumerate(heights))
83107
```
84108

85109
### **Java**

‎solution/0000-0099/0084.Largest Rectangle in Histogram/README_EN.md‎

Lines changed: 25 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -40,7 +40,7 @@ The largest rectangle is shown in the red area, which has an area = 10 units.
4040
```python
4141
class Solution:
4242
def largestRectangleArea(self, heights: List[int]) -> int:
43-
res, n =0, len(heights)
43+
n = len(heights)
4444
stk = []
4545
left = [-1] * n
4646
right = [n] * n
@@ -51,9 +51,31 @@ class Solution:
5151
if stk:
5252
left[i] = stk[-1]
5353
stk.append(i)
54+
return max(h * (right[i] - left[i] - 1) for i, h in enumerate(heights))
55+
```
56+
57+
```python
58+
class Solution:
59+
def largestRectangleArea(self, heights: List[int]) -> int:
60+
n = len(heights)
61+
stk = []
62+
left = [-1] * n
63+
right = [n] * n
5464
for i, h in enumerate(heights):
55-
res = max(res, h * (right[i] - left[i] - 1))
56-
return res
65+
while stk and heights[stk[-1]] >= h:
66+
stk.pop()
67+
if stk:
68+
left[i] = stk[-1]
69+
stk.append(i)
70+
stk = []
71+
for i in range(n - 1, -1, -1):
72+
h = heights[i]
73+
while stk and heights[stk[-1]] >= h:
74+
stk.pop()
75+
if stk:
76+
right[i] = stk[-1]
77+
stk.append(i)
78+
return max(h * (right[i] - left[i] - 1) for i, h in enumerate(heights))
5779
```
5880

5981
### **Java**
Lines changed: 2 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -1,6 +1,6 @@
11
class Solution:
22
def largestRectangleArea(self, heights: List[int]) -> int:
3-
res, n =0, len(heights)
3+
n = len(heights)
44
stk = []
55
left = [-1] * n
66
right = [n] * n
@@ -11,6 +11,4 @@ def largestRectangleArea(self, heights: List[int]) -> int:
1111
if stk:
1212
left[i] = stk[-1]
1313
stk.append(i)
14-
for i, h in enumerate(heights):
15-
res = max(res, h * (right[i] - left[i] - 1))
16-
return res
14+
return max(h * (right[i] - left[i] - 1) for i, h in enumerate(heights))

‎solution/0000-0099/0085.Maximal Rectangle/README.md‎

Lines changed: 171 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -61,22 +61,192 @@
6161

6262
<!-- 这里可写通用的实现逻辑 -->
6363

64+
**方法一:单调栈**
65+
66+
把每一行视为柱状图的底部,对每一行求柱状图的最大面积即可。
67+
68+
时间复杂度 $O(mn),ドル其中 $m$ 表示 $matrix$ 的行数,$n$ 表示 $matrix$ 的列数。
69+
6470
<!-- tabs:start -->
6571

6672
### **Python3**
6773

6874
<!-- 这里可写当前语言的特殊实现逻辑 -->
6975

7076
```python
71-
77+
class Solution:
78+
def maximalRectangle(self, matrix: List[List[str]]) -> int:
79+
heights = [0] * len(matrix[0])
80+
ans = 0
81+
for row in matrix:
82+
for j, v in enumerate(row):
83+
if v == "1":
84+
heights[j] += 1
85+
else:
86+
heights[j] = 0
87+
ans = max(ans, self.largestRectangleArea(heights))
88+
return ans
89+
90+
def largestRectangleArea(self, heights: List[int]) -> int:
91+
n = len(heights)
92+
stk = []
93+
left = [-1] * n
94+
right = [n] * n
95+
for i, h in enumerate(heights):
96+
while stk and heights[stk[-1]] >= h:
97+
stk.pop()
98+
if stk:
99+
left[i] = stk[-1]
100+
stk.append(i)
101+
stk = []
102+
for i in range(n - 1, -1, -1):
103+
h = heights[i]
104+
while stk and heights[stk[-1]] >= h:
105+
stk.pop()
106+
if stk:
107+
right[i] = stk[-1]
108+
stk.append(i)
109+
return max(h * (right[i] - left[i] - 1) for i, h in enumerate(heights))
72110
```
73111

74112
### **Java**
75113

76114
<!-- 这里可写当前语言的特殊实现逻辑 -->
77115

78116
```java
117+
class Solution {
118+
public int maximalRectangle(char[][] matrix) {
119+
int n = matrix[0].length;
120+
int[] heights = new int[n];
121+
int ans = 0;
122+
for (var row : matrix) {
123+
for (int j = 0; j < n; ++j) {
124+
if (row[j] == '1') {
125+
heights[j] += 1;
126+
} else {
127+
heights[j] = 0;
128+
}
129+
}
130+
ans = Math.max(ans, largestRectangleArea(heights));
131+
}
132+
return ans;
133+
}
134+
135+
private int largestRectangleArea(int[] heights) {
136+
int res = 0, n = heights.length;
137+
Deque<Integer> stk = new ArrayDeque<>();
138+
int[] left = new int[n];
139+
int[] right = new int[n];
140+
Arrays.fill(right, n);
141+
for (int i = 0; i < n; ++i) {
142+
while (!stk.isEmpty() && heights[stk.peek()] >= heights[i]) {
143+
right[stk.pop()] = i;
144+
}
145+
left[i] = stk.isEmpty() ? -1 : stk.peek();
146+
stk.push(i);
147+
}
148+
for (int i = 0; i < n; ++i) {
149+
res = Math.max(res, heights[i] * (right[i] - left[i] - 1));
150+
}
151+
return res;
152+
}
153+
}
154+
```
155+
156+
### **C++**
157+
158+
```cpp
159+
class Solution {
160+
public:
161+
int maximalRectangle(vector<vector<char>>& matrix) {
162+
int n = matrix[0].size();
163+
vector<int> heights(n);
164+
int ans = 0;
165+
for (auto& row : matrix)
166+
{
167+
for (int j = 0; j < n; ++j)
168+
{
169+
if (row[j] == '1') ++heights[j];
170+
else heights[j] = 0;
171+
}
172+
ans = max(ans, largestRectangleArea(heights));
173+
}
174+
return ans;
175+
}
176+
177+
int largestRectangleArea(vector<int>& heights) {
178+
int res = 0, n = heights.size();
179+
stack<int> stk;
180+
vector<int> left(n, -1);
181+
vector<int> right(n, n);
182+
for (int i = 0; i < n; ++i)
183+
{
184+
while (!stk.empty() && heights[stk.top()] >= heights[i])
185+
{
186+
right[stk.top()] = i;
187+
stk.pop();
188+
}
189+
if (!stk.empty()) left[i] = stk.top();
190+
stk.push(i);
191+
}
192+
for (int i = 0; i < n; ++i)
193+
res = max(res, heights[i] * (right[i] - left[i] - 1));
194+
return res;
195+
}
196+
};
197+
```
79198

199+
### **Go**
200+
201+
```go
202+
func maximalRectangle(matrix [][]byte) int {
203+
n := len(matrix[0])
204+
heights := make([]int, n)
205+
ans := 0
206+
for _, row := range matrix {
207+
for j, v := range row {
208+
if v == '1' {
209+
heights[j]++
210+
} else {
211+
heights[j] = 0
212+
}
213+
}
214+
ans = max(ans, largestRectangleArea(heights))
215+
}
216+
return ans
217+
}
218+
219+
func largestRectangleArea(heights []int) int {
220+
res, n := 0, len(heights)
221+
var stk []int
222+
left, right := make([]int, n), make([]int, n)
223+
for i := range right {
224+
right[i] = n
225+
}
226+
for i, h := range heights {
227+
for len(stk) > 0 && heights[stk[len(stk)-1]] >= h {
228+
right[stk[len(stk)-1]] = i
229+
stk = stk[:len(stk)-1]
230+
}
231+
if len(stk) > 0 {
232+
left[i] = stk[len(stk)-1]
233+
} else {
234+
left[i] = -1
235+
}
236+
stk = append(stk, i)
237+
}
238+
for i, h := range heights {
239+
res = max(res, h*(right[i]-left[i]-1))
240+
}
241+
return res
242+
}
243+
244+
func max(a, b int) int {
245+
if a > b {
246+
return a
247+
}
248+
return b
249+
}
80250
```
81251

82252
### **...**

0 commit comments

Comments
(0)

AltStyle によって変換されたページ (->オリジナル) /