| 学习笔记 | |
| |#|Title|Solutions| | |
| |---|---|------| | |
| |-1|[sort](sort) | 冒泡/选择/插入/归并/快速/归并排序([Go](../Week_08/sort/sort.go),[Py](../Week_08/sort/sort.py))| | |
| |191|[number-of-1-bits](https://leetcode-cn.com/problems/number-of-1-bits) | 依次除2([Go](../Week_08/191/number_of_1_bits.go),[Py](../Week_08/191/number_of_1_bits.py)),按位与n-1([Go](../Week_08/191/number_of_1_bits2.go),[Py](../Week_08/191/number_of_1_bits2.py))| | |
| |190|[reverse_bits](https://leetcode-cn.com/problems/reverse_bits) | 迭代([Go](../Week_08/190/reverse_bits.go),[Py](../Week_08/190/reverse_bits.py)),分治位运算([Go](../Week_08/190/reverse_bits2.go),[Py](../Week_08/190/reverse_bits2.py))| | |
| |338|[counting-bits](https://leetcode-cn.com/problems/counting-bits) | 动态规划1([Go](../Week_08/338/counting_bits.go),[Py](../Week_08/338/counting_bits.py)),动态规划2([Go](../Week_08/338/counting_bits2.go),[Py](../Week_08/338/counting_bits2.py))| | |
| |231|[power-of-two](https://leetcode-cn.com/problems/power-of-two) | 位运算1([Go](../Week_08/231/power_of_two.go),[Py](../Week_08/231/power_of_two.py)),位运算2([Go](../Week_08/231/power_of_two2.go),[Py](../Week_08/231/power_of_two2.py))| | |
| |326|[power-of-three](https://leetcode-cn.com/problems/power-of-three) | 累除法([Go](../Week_08/326/power_of_three.go),[Py](../Week_08/326/power_of_three.py)),累乘法([Go](../Week_08/326/power_of_three2.go),[Py](../Week_08/326/power_of_three2.py))| | |
| |342|[power-of-four](https://leetcode-cn.com/problems/power-of-four) | 累除法([Go](../Week_08/342/power_of_four.go),[Py](../Week_08/342/power_of_four.py)),位运算([Go](../Week_08/342/power_of_four2.go),[Py](../Week_08/342/power_of_four2.py))| | |
| |146|[lru-cache](https://leetcode-cn.com/problems/lru-cache) | 双向链表+字典([Go](../Week_08/146/lru_cache.go),[Py](../Week_08/146/lru_cache.py))| | |
| |1122|[relative-sort-array](https://leetcode-cn.com/problems/relative-sort-array)| 计数排序([Go](../Week_08/1122/relative_sort_array.go),[Py](../Week_08/1122/relative_sort_array.py))| | |
| |56|[merge-intervals](https://leetcode-cn.com/problems/merge-intervals)| 计数排序([Go](../Week_08/56/merge_intervals.go),[Py](../Week_08/56/merge_intervals.py))| | |
| |453|[reverse-pairs](https://leetcode-cn.com/problems/reverse-pairs)| 二分查找和插入([Go](../Week_08/493/reverse_pairs.go),[Py](../Week_08/493/reverse_pairs.py))| | |
| ## 题解 | |
| ### 191. number-of-1-bits | |
| 1. 除2：依次除2，看余数是否是1 | |
| 2. 按位与n-1: n & n-1 会消去最后一个1 | |
| ### 190. reverse-bits | |
| 1. 除2： | |
| 2. 分治：依次以16、8、4、2、1两两交换 | |
| ### 338. counting-bits | |
| 1. 动态规划1： dp[i] = dp[i//2] + i % 2 | |
| 2. 动态规划2： dp[i] = dp[i & (i-1)] + 1 | |
| ### 231. power-of-two | |
| 1. 位运算1： n & (n-1)为消去最后一个1 | |
| 2. 位运算2： n & -n会保留最后一个1，其他位都置0 | |
| ### 326. power-of-three | |
| 1. 累除法 | |
| 2. 累乘法 | |
| ### 342. power-of-four | |
| 1. 累除法 | |
| 2. 位运算 | |
| ### 146. lru_cache | |
| 1. 双向链表+字典 | |
| ### 493. reverse-pairs | |
| 1. 二分查找: 逆序遍历nums, num[i]在有序数组arr的位置即为nums[i]的对数,随后将num[i]*2二分查找插入arr | |