解决64 1283

Author: LuYanFCP

README.md

@@ -6,7 +6,8 @@
 
 ## 位运算
 
-No.136 [cpp](cpp/136.cpp)
++ No.136 [cpp](cpp/136.cpp)
++ No.64 [cpp](cpp/64.cpp) [python](python/64.py)
 
 ### 散列表（HashTable）
 
@@ -15,7 +16,7 @@ No.136 [cpp](cpp/136.cpp)
 
 ## 二叉树
 
-#### 二叉树的遍历
+### 二叉树的遍历
 
 + No.113: [cpp](cpp/113.cpp) [python](python/113.py)
 
@@ -37,8 +38,12 @@ No.136 [cpp](cpp/136.cpp)
 
 ## 前缀和/树状数组
 
-No.303 [cpp](cpp/303.cpp)
-No.307 [cpp](cpp/307.cpp)
++ No.303 [cpp](cpp/303.cpp)
++ No.307 [cpp](cpp/307.cpp)
+
+## 二分
+
++ No.128 [cpp](cpp/128.cpp) [python](python/128.py)
 
 ### 剑指offer系列
 

cpp/1283.cpp

@@ -0,0 +1,29 @@
+#include <algorithm>
+#include <vector>
+using namespace std;
+
+class Solution {
+public:
+    int smallestDivisor(vector<int>& nums, int threshold) {
+        int end = *max_element(nums.cbegin(), nums.cend());
+        int begin = 1;
+        int mid, _sum, res = -1;
+        while (end > begin) {
+            mid = (end - begin)/2 + begin;
+            _sum = 0;
+            for (int num: nums) {
+                _sum += (num - 1 + mid)/mid;
+            }
+
+            if (_sum > threshold) {
+                begin = mid+1;
+            } else {
+                end = mid;
+            }
+        }
+        return end;
+
+    }
+
+
+};

cpp/64.cpp

@@ -0,0 +1,12 @@
+class Solution {
+public:
+    int sumNums(int n) {
+        int sum = 0;
+        _sum(n, sum);
+        return sum;
+    }
+    int _sum(int n, int &sum) {
+        sum += n;
+        return n && _sum(n-1, sum);
+    }
+};

python/1283.py

@@ -0,0 +1,13 @@
+class Solution:
+    def smallestDivisor(self, nums: List[int], threshold: int) -> int:
+        begin, end = 1, max(nums)+1
+        while begin < end:
+            mid = (end - begin)//2 + begin
+            _sum = 0
+            for num in nums:
+                _sum += (num + mid - 1) // mid
+            if _sum <= threshold:
+                end = mid
+            else:
+                begin = mid + 1
+        return end

python/64.py

@@ -0,0 +1,12 @@
+class Solution:
+    def sumNums(self, n: int) -> int:
+        """
+        使用and运算符短路
+        """
+        sum_val = 0       
+        def _sum(n):
+            nonlocal sum_val
+            sum_val += n
+            return n and _sum(n-1)
+        _sum(n)
+        return sum_val