Solution for 1003, 1004 problems

Author: Garvit244

1000-1100q/1003.py

@@ -0,0 +1,67 @@
+'''
+We are given that the string "abc" is valid.
+
+From any valid string V, we may split V into two pieces X and Y such that X + Y (X concatenated with Y) is equal to V.  (X or Y may be empty.)  Then, X + "abc" + Y is also valid.
+
+If for example S = "abc", then examples of valid strings are: "abc", "aabcbc", "abcabc", "abcabcababcc".  Examples of invalid strings are: "abccba", "ab", "cababc", "bac".
+
+Return true if and only if the given string S is valid.
+
+ 
+
+Example 1:
+
+Input: "aabcbc"
+Output: true
+Explanation: 
+We start with the valid string "abc".
+Then we can insert another "abc" between "a" and "bc", resulting in "a" + "abc" + "bc" which is "aabcbc".
+Example 2:
+
+Input: "abcabcababcc"
+Output: true
+Explanation: 
+"abcabcabc" is valid after consecutive insertings of "abc".
+Then we can insert "abc" before the last letter, resulting in "abcabcab" + "abc" + "c" which is "abcabcababcc".
+Example 3:
+
+Input: "abccba"
+Output: false
+Example 4:
+
+Input: "cababc"
+Output: false
+ 
+
+Note:
+
+1 <= S.length <= 20000
+S[i] is 'a', 'b', or 'c'
+'''
+
+class Solution(object):
+    def isValid(self, S):
+        """
+        :type S: str
+        :rtype: bool
+        """
+        stack = []
+        if not S:
+            return False
+        
+        for char in S:
+            if char == 'a':
+                stack.append('a')
+            if char == 'b':
+                if not stack:
+                    return False
+                if stack[-1] == 'a':
+                    stack.pop()
+                    stack.append(char)
+            if char == 'c':
+                if not stack:
+                    return False
+                if stack[-1] == 'b':
+                    stack.pop()
+        return len(stack) == 0
+ 

1000-1100q/1004.py

@@ -0,0 +1,44 @@
+'''
+Given an array A of 0s and 1s, we may change up to K values from 0 to 1.
+
+Return the length of the longest (contiguous) subarray that contains only 1s. 
+
+ 
+
+Example 1:
+
+Input: A = [1,1,1,0,0,0,1,1,1,1,0], K = 2
+Output: 6
+Explanation: 
+[1,1,1,0,0,1,1,1,1,1,1]
+Bolded numbers were flipped from 0 to 1.  The longest subarray is underlined.
+Example 2:
+
+Input: A = [0,0,1,1,0,0,1,1,1,0,1,1,0,0,0,1,1,1,1], K = 3
+Output: 10
+Explanation: 
+[0,0,1,1,1,1,1,1,1,1,1,1,0,0,0,1,1,1,1]
+Bolded numbers were flipped from 0 to 1.  The longest subarray is underlined.
+ 
+
+Note:
+
+1 <= A.length <= 20000
+0 <= K <= A.length
+A[i] is 0 or 1 
+'''
+
+class Solution(object):
+    def longestOnes(self, A, K):
+        """
+        :type A: List[int]
+        :type K: int
+        :rtype: int
+        """
+        start_index = 0
+        for end_index in range(0, len(A)):
+            K -= 1-A[end_index]
+            if K < 0:
+                K += 1-A[start_index]
+                start_index += 1
+        return end_index-start_index+1

README.md

@@ -14,6 +14,8 @@ Python solution of problems from [LeetCode](https://leetcode.com/).
 |1014|[Capacity To Ship Packages Within D Days](https://leetcode.com/problems/capacity-to-ship-packages-within-d-days/) | [Python](./1000-1100q/1014.py) | Medium|
 |1013|[Pairs of Songs With Total Durations Divisible by 60](https://leetcode.com/problems/pairs-of-songs-with-total-durations-divisible-by-60/)|[Python](./1000-1100q/1013.py)|Easy|
 |1012|[Complement of Base 10 Integer](https://leetcode.com/problems/complement-of-base-10-integer/) | [Python](./1000-1100q/1012.py)|Easy|
+|1004|[Max Consecutive Ones III](https://leetcode.com/problems/max-consecutive-ones-iii)|[Python](./1000-1100q/1004.py)|Medium|
+|1003|[Check If Word Is Valid After Substitutions](https://leetcode.com/problems/check-if-word-is-valid-after-substitutions)|[Python](./1000-1100q/1003.py)|Medium|
 |1002|[Find Common Characters](https://leetcode.com/problems/find-common-characters)|[Python](./1000-1100q/1002.py)|Easy|
 
 ##### [Problems 900-1000](./900-1000q/)