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Commit 8b6af50

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feat: add solutions to lcof2 problems: No.004,005,006
1 parent acb1e14 commit 8b6af50

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13 files changed

+281
-4
lines changed

13 files changed

+281
-4
lines changed

‎lcof2/剑指 Offer II 002. 二进制加法/README.md‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -41,7 +41,7 @@
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<!-- 这里可写通用的实现逻辑 -->
4343

44-
模拟笔算加法的过程,注意进位
44+
统计所有数字每个位中 1 出现的次数,对于某个位,1 出现的次数一定是 3 的倍数 +1 或 0。对这个数 %3 得到的结果就是那个出现一次的数字在该位上的值。
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<!-- tabs:start -->
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‎lcof2/剑指 Offer II 004. 只出现一次的数字/README.md‎

Lines changed: 45 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -45,22 +45,66 @@
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<!-- 这里可写通用的实现逻辑 -->
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一位一位计算出结果
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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
55-
57+
class Solution:
58+
def singleNumber(self, nums: List[int]) -> int:
59+
ans = 0
60+
for i in range(0, 32):
61+
cnt = sum(num >> i & 1 for num in nums)
62+
if cnt % 3:
63+
if i == 31:
64+
ans -= 1 << i
65+
else:
66+
ans |= 1 << i
67+
return ans
5668
```
5769

5870
### **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
75+
class Solution {
76+
public int singleNumber(int[] nums) {
77+
int ans = 0;
78+
for (int i = 0; i < 32; i++) {
79+
int cnt = 0;
80+
for (int num : nums) {
81+
cnt += num >> i & 1;
82+
}
83+
cnt %= 3;
84+
ans |= cnt << i;
85+
}
86+
return ans;
87+
}
88+
}
89+
```
6390

91+
### **Go**
92+
93+
需要注意 Golang 中的 `int` 在 64 位平台上相当于 `int64`
94+
95+
```go
96+
func singleNumber(nums []int) int {
97+
ans := int32(0)
98+
for i := 0; i < 32; i++ {
99+
cnt := int32(0)
100+
for _, num := range nums {
101+
cnt += int32(num) >> i & 1
102+
}
103+
cnt %= 3
104+
ans |= cnt << i
105+
}
106+
return int(ans)
107+
}
64108
```
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### **...**
Lines changed: 12 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,12 @@
1+
func singleNumber(nums []int) int {
2+
ans := int32(0)
3+
for i := 0; i < 32; i++ {
4+
cnt := int32(0)
5+
for _, num := range nums {
6+
cnt += int32(num) >> i & 1
7+
}
8+
cnt %= 3
9+
ans |= cnt << i
10+
}
11+
return int(ans)
12+
}
Lines changed: 14 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,14 @@
1+
class Solution {
2+
public int singleNumber(int[] nums) {
3+
int ans = 0;
4+
for (int i = 0; i < 32; i++) {
5+
int cnt = 0;
6+
for (int num : nums) {
7+
cnt += num >> i & 1;
8+
}
9+
cnt %= 3;
10+
ans |= cnt << i;
11+
}
12+
return ans;
13+
}
14+
}
Lines changed: 11 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,11 @@
1+
class Solution:
2+
def singleNumber(self, nums: List[int]) -> int:
3+
ans = 0
4+
for i in range(0, 32):
5+
cnt = sum(num >> i & 1 for num in nums)
6+
if cnt % 3:
7+
if i == 31:
8+
ans -= 1 << i
9+
else:
10+
ans |= 1 << i
11+
return ans

‎lcof2/剑指 Offer II 005. 单词长度的最大乘积/README.md‎

Lines changed: 64 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -49,22 +49,85 @@
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<!-- 这里可写通用的实现逻辑 -->
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52+
因为只有 26 个小写字符,所以可以用一个 `int32` 存储字符的出现情况,然后枚举最大乘积
53+
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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
59-
61+
class Solution:
62+
def maxProduct(self, words: List[str]) -> int:
63+
n = len(words)
64+
mask = [0 for _ in range(n)]
65+
for i, word in enumerate(words):
66+
for ch in word:
67+
mask[i] |= 1 << (ord(ch) - ord('a'))
68+
ans = 0
69+
for i in range(0, n - 1):
70+
for j in range(i + 1, n):
71+
if mask[i] & mask[j] == 0:
72+
ans = max(ans, len(words[i]) * len(words[j]))
73+
return ans
6074
```
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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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6680
```java
81+
class Solution {
82+
public int maxProduct(String[] words) {
83+
int n = words.length;
84+
int[] mask = new int[n];
85+
for (int i = 0; i < n; i++) {
86+
for (char ch : words[i].toCharArray()) {
87+
mask[i] |= 1 << (ch - 'a');
88+
}
89+
}
90+
int ans = 0;
91+
for (int i = 0; i < n - 1; i++) {
92+
for (int j = i + 1; j < n; j++) {
93+
if ((mask[i] & mask[j]) == 0) {
94+
ans = Math.max(ans, words[i].length() * words[j].length());
95+
}
96+
}
97+
}
98+
return ans;
99+
}
100+
}
101+
```
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103+
### **Go**
104+
105+
```go
106+
func maxProduct(words []string) int {
107+
n := len(words)
108+
mask := make([]int32, n)
109+
for i, word := range words {
110+
for _, r := range word {
111+
mask[i] |= 1 << (r - 'a')
112+
}
113+
}
114+
ans := 0
115+
for i := 0; i < n-1; i++ {
116+
for j := i + 1; j < n; j++ {
117+
if mask[i]&mask[j] == 0 {
118+
ans = max(ans, len(words[i])*len(words[j]))
119+
}
120+
}
121+
}
122+
return ans
123+
}
124+
125+
func max(a, b int) int {
126+
if a > b {
127+
return a
128+
}
129+
return b
130+
}
68131
```
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### **...**
Lines changed: 25 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,25 @@
1+
func maxProduct(words []string) int {
2+
n := len(words)
3+
mask := make([]int32, n)
4+
for i, word := range words {
5+
for _, r := range word {
6+
mask[i] |= 1 << (r - 'a')
7+
}
8+
}
9+
ans := 0
10+
for i := 0; i < n-1; i++ {
11+
for j := i + 1; j < n; j++ {
12+
if mask[i]&mask[j] == 0 {
13+
ans = max(ans, len(words[i])*len(words[j]))
14+
}
15+
}
16+
}
17+
return ans
18+
}
19+
20+
func max(a, b int) int {
21+
if a > b {
22+
return a
23+
}
24+
return b
25+
}
Lines changed: 20 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,20 @@
1+
class Solution {
2+
public int maxProduct(String[] words) {
3+
int n = words.length;
4+
int[] mask = new int[n];
5+
for (int i = 0; i < n; i++) {
6+
for (char ch : words[i].toCharArray()) {
7+
mask[i] |= 1 << (ch - 'a');
8+
}
9+
}
10+
int ans = 0;
11+
for (int i = 0; i < n - 1; i++) {
12+
for (int j = i + 1; j < n; j++) {
13+
if ((mask[i] & mask[j]) == 0) {
14+
ans = Math.max(ans, words[i].length() * words[j].length());
15+
}
16+
}
17+
}
18+
return ans;
19+
}
20+
}
Lines changed: 13 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,13 @@
1+
class Solution:
2+
def maxProduct(self, words: List[str]) -> int:
3+
n = len(words)
4+
mask = [0 for _ in range(n)]
5+
for i, word in enumerate(words):
6+
for ch in word:
7+
mask[i] |= 1 << (ord(ch) - ord('a'))
8+
ans = 0
9+
for i in range(0, n - 1):
10+
for j in range(i + 1, n):
11+
if mask[i] & mask[j] == 0:
12+
ans = max(ans, len(words[i]) * len(words[j]))
13+
return ans

‎lcof2/剑指 Offer II 006. 排序数组中两个数字之和/README.md‎

Lines changed: 41 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -55,22 +55,62 @@
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<!-- 这里可写通用的实现逻辑 -->
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58+
双指针
59+
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<!-- tabs:start -->
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6062
### **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
65-
67+
class Solution:
68+
def twoSum(self, numbers: List[int], target: int) -> List[int]:
69+
i, j = 0, len(numbers) - 1
70+
while True:
71+
if numbers[i] + numbers[j] < target:
72+
i += 1
73+
elif numbers[i] + numbers[j] > target:
74+
j -= 1
75+
else:
76+
return [i, j]
6677
```
6778

6879
### **Java**
6980

7081
<!-- 这里可写当前语言的特殊实现逻辑 -->
7182

7283
```java
84+
class Solution {
85+
public int[] twoSum(int[] numbers, int target) {
86+
int i = 0, j = numbers.length - 1;
87+
for (;;) {
88+
if (numbers[i] + numbers[j] < target) {
89+
i++;
90+
} else if (numbers[i] + numbers[j] > target) {
91+
j--;
92+
} else {
93+
return new int[]{i, j};
94+
}
95+
}
96+
}
97+
}
98+
```
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100+
### **Go**
101+
102+
```go
103+
func twoSum(numbers []int, target int) []int {
104+
for i, j := 0, len(numbers)-1; ; {
105+
if numbers[i]+numbers[j] < target {
106+
i++
107+
} else if numbers[i]+numbers[j] > target {
108+
j--
109+
} else {
110+
return []int{i, j}
111+
}
112+
}
113+
}
74114
```
75115

76116
### **...**

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