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feat: add solutions to leetcode problems: No.0121,0122
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9 files changed

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‎solution/0100-0199/0121.Best Time to Buy and Sell Stock/README.md

Lines changed: 22 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -37,15 +37,35 @@
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<!-- 这里可写当前语言的特殊实现逻辑 -->
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```python
40-
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class Solution:
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def maxProfit(self, prices: List[int]) -> int:
42+
if not prices:
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return 0
44+
res = 0
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min_price = prices[0]
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for price in prices:
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min_price = min(min_price, price)
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res = max(res, price - min_price)
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return res
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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
48-
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class Solution {
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public int maxProfit(int[] prices) {
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if (prices == null) return 0;
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int res = 0;
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int min = Integer.MAX_VALUE;
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for (int price : prices) {
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min = Math.min(min, price);
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res = Math.max(res, price - min);
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}
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return res;
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}
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}
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```
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### **...**

‎solution/0100-0199/0121.Best Time to Buy and Sell Stock/README_EN.md

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Original file line numberDiff line numberDiff line change
@@ -43,13 +43,33 @@
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### **Python3**
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```python
46-
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class Solution:
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def maxProfit(self, prices: List[int]) -> int:
48+
if not prices:
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return 0
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res = 0
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min_price = prices[0]
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for price in prices:
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min_price = min(min_price, price)
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res = max(res, price - min_price)
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return res
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```
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### **Java**
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```java
52-
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class Solution {
62+
public int maxProfit(int[] prices) {
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if (prices == null) return 0;
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int res = 0;
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int min = Integer.MAX_VALUE;
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for (int price : prices) {
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min = Math.min(min, price);
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res = Math.max(res, price - min);
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}
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return res;
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}
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}
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```
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### **...**

‎solution/0100-0199/0121.Best Time to Buy and Sell Stock/Solution.java

Lines changed: 7 additions & 11 deletions
Original file line numberDiff line numberDiff line change
@@ -1,16 +1,12 @@
11
class Solution {
22
public int maxProfit(int[] prices) {
3-
if (prices.length == 0) return 0;
4-
int m = prices[0] , l = 0;
5-
for (int i = 1; i < prices.length; i++) {
6-
int d = prices[i];
7-
if (d < m) {
8-
m = d;
9-
} else {
10-
int n = d - m;
11-
l = n > l ? n : l;
12-
}
3+
if (prices == null) return 0;
4+
int res = 0;
5+
int min = Integer.MAX_VALUE;
6+
for (int price : prices) {
7+
min = Math.min(min, price);
8+
res = Math.max(res, price - min);
139
}
14-
return l;
10+
return res;
1511
}
1612
}

‎solution/0100-0199/0121.Best Time to Buy and Sell Stock/Solution.py

Lines changed: 8 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -1,10 +1,10 @@
11
class Solution:
22
def maxProfit(self, prices: List[int]) -> int:
3-
minprice = (1 << 31) -1
4-
maxprofit = 0
5-
for i in range(len(prices)):
6-
if prices[i] <= minprice:
7-
minprice = prices[i]
8-
elif prices[i] - minprice > maxprofit:
9-
maxprofit = prices[i] - minprice
10-
return maxprofit
3+
if not prices:
4+
return 0
5+
res = 0
6+
min_price = prices[0]
7+
for price in prices:
8+
min_price = min(min_price, price)
9+
res = max(res, price - min_price)
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return res

‎solution/0100-0199/0122.Best Time to Buy and Sell Stock II/README.md

Lines changed: 40 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -38,22 +38,61 @@
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<!-- 这里可写通用的实现逻辑 -->
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所有上涨交易日都做买卖，所有下跌交易日都不做买卖，这样便能实现利润最大化。
42+
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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
48-
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class Solution:
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def maxProfit(self, prices: List[int]) -> int:
52+
if not prices:
53+
return 0
54+
res = 0
55+
for i in range(1, len(prices)):
56+
t = prices[i] - prices[i - 1]
57+
res += max(t, 0)
58+
return res
4959
```
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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
66+
class Solution {
67+
public int maxProfit(int[] prices) {
68+
if (prices == null) return 0;
69+
int res = 0;
70+
for (int i = 1, n = prices.length; i < n; ++i) {
71+
// 策略是所有上涨交易日都做买卖，所以下跌交易日都不做买卖
72+
int t = prices[i] - prices[i - 1];
73+
res += Math.max(t, 0);
74+
}
75+
return res;
76+
}
77+
}
78+
```
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### **C++**
81+
82+
```cpp
83+
class Solution {
84+
public:
85+
int maxProfit(vector<int>& prices) {
86+
int res = 0, n;
87+
if ((n = prices.size()) == 0) return 0;
88+
for (int i = 1; i < n; ++i)
89+
{
90+
int t = prices[i] - prices[i - 1];
91+
res += max(0, t);
92+
}
93+
return res;
94+
}
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};
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```
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### **...**

‎solution/0100-0199/0122.Best Time to Buy and Sell Stock II/README_EN.md

Lines changed: 38 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -57,13 +57,50 @@
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### **Python3**
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```python
60-
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class Solution:
61+
def maxProfit(self, prices: List[int]) -> int:
62+
if not prices:
63+
return 0
64+
res = 0
65+
for i in range(1, len(prices)):
66+
t = prices[i] - prices[i - 1]
67+
res += max(t, 0)
68+
return res
6169
```
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### **Java**
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```java
74+
class Solution {
75+
public int maxProfit(int[] prices) {
76+
if (prices == null) return 0;
77+
int res = 0;
78+
for (int i = 1, n = prices.length; i < n; ++i) {
79+
// 策略是所有上涨交易日都做买卖，所以下跌交易日都不做买卖
80+
int t = prices[i] - prices[i - 1];
81+
res += Math.max(t, 0);
82+
}
83+
return res;
84+
}
85+
}
86+
```
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88+
### **C++**
89+
90+
```cpp
91+
class Solution {
92+
public:
93+
int maxProfit(vector<int>& prices) {
94+
int res = 0, n;
95+
if ((n = prices.size()) == 0) return 0;
96+
for (int i = 1; i < n; ++i)
97+
{
98+
int t = prices[i] - prices[i - 1];
99+
res += max(0, t);
100+
}
101+
return res;
102+
}
103+
};
67104
```
68105
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### **...**

‎solution/0100-0199/0122.Best Time to Buy and Sell Stock II/Solution.cpp

Lines changed: 9 additions & 11 deletions
Original file line numberDiff line numberDiff line change
@@ -1,15 +1,13 @@
1-
public:
2-
int maxProfit(vector<int>& prices)
3-
{
4-
if (0 == prices.size())
5-
return 0 ;
6-
int M = 0 ;
7-
for (int i = 1; i < prices.size(); ++i)
1+
class Solution {
2+
public:
3+
int maxProfit(vector<int>& prices) {
4+
int res = 0, n;
5+
if ((n = prices.size()) == 0) return 0;
6+
for (int i = 1; i < n; ++i)
87
{
9-
int d = prices[i] - prices[i-1] ;
10-
if (d > 0)
11-
M += d ;
8+
int t = prices[i] - prices[i - 1];
9+
res += max(0, t);
1210
}
13-
return M ;
11+
return res;
1412
}
1513
};

‎solution/0100-0199/0122.Best Time to Buy and Sell Stock II/Solution.java

Lines changed: 6 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -1,11 +1,11 @@
11
class Solution {
22
public int maxProfit(int[] prices) {
3-
int maxProfit = 0;
4-
for (int i = 0; i < prices.length; i++) {
5-
if (i + 1 < prices.length && prices[i + 1] - prices[i] > 0) {
6-
maxProfit += prices[i + 1] - prices[i];
7-
}
3+
if (prices == null) return 0;
4+
int res = 0;
5+
for (int i = 1, n = prices.length; i < n; ++i) {
6+
int t = prices[i] - prices[i - 1];
7+
res += Math.max(t, 0);
88
}
9-
return maxProfit;
9+
return res;
1010
}
1111
}

‎solution/0100-0199/0122.Best Time to Buy and Sell Stock II/Solution.py

Lines changed: 7 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -1,7 +1,9 @@
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class Solution:
22
def maxProfit(self, prices: List[int]) -> int:
3-
maxprofit = 0
4-
for i in range(0, len(prices) - 1, 1):
5-
if prices[i + 1] > prices[i]:
6-
maxprofit += prices[i + 1] - prices[i]
7-
return maxprofit
3+
if not prices:
4+
return 0
5+
res = 0
6+
for i in range(1, len(prices)):
7+
t = prices[i] - prices[i - 1]
8+
res += max(t, 0)
9+
return res

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