Merge pull request #332 from haofengsiji/master

Update 0474.一和零.md

problems/0474.一和零.md

@@ -190,16 +190,18 @@ class Solution {
 ```
 
 Python：
-```python
+```python3
 class Solution:
     def findMaxForm(self, strs: List[str], m: int, n: int) -> int:
-        dp = [[0] * (n + 1) for _ in range(m + 1)]
+        dp = [[0] * (n + 1) for _ in range(m + 1)]	# 默认初始化0
+        # 遍历物品
         for str in strs:
-            oneNum = str.count('1')
-            zeroNum = str.count('0')
-            for i in range(m, zeroNum - 1, -1):
-                for j in range(n, oneNum - 1, -1):
-                    dp[i][j] = max(dp[i][j], dp[i - zeroNum][j - oneNum] + 1)
+            ones = str.count('1')
+            zeros = str.count('0')
+            # 遍历背包容量且从后向前遍历！
+            for i in range(m, zeros - 1, -1):
+                for j in range(n, ones - 1, -1):
+                    dp[i][j] = max(dp[i][j], dp[i - zeros][j - ones] + 1)
         return dp[m][n]
 ```