927

Author: ProHiryu

Math/927.md

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+## 3Sum With Multiplicity
+
+#### Description
+
+[link](https://leetcode.com/problems/927)
+
+---
+
+#### Solution
+
+- See Code
+
+---
+
+#### Code
+
+> Complexity T : O(n) M : O(n)
+
+```python
+class Solution:
+    def threeEqualParts(self, A: List[int]) -> List[int]:
+        
+        num_ones = sum(A)
+        
+        if num_ones == 0:
+            return [0, 2]
+        
+        if num_ones % 3 != 0:
+            return [-1, -1]
+        
+        c = 0
+        s1 = s2 = s3 = -1
+        for idx,x in enumerate(A):
+			# Find the first 1 in each part
+            if x == 1:
+                c += 1
+            
+            if c == 1 and s1 < 0:
+                s1 = idx
+                
+            if c == num_ones//3 + 1 and s2 < 0:
+                s2 = idx
+                
+            if c == num_ones*2//3 + 1 and s3 < 0:
+                s3 = idx
+                break
+                
+        n = len(A[s3:]) # The length of each part when all the leading 0's are removed
+        
+        if A[s1:s1+n] == A[s2:s2+n] and A[s2:s2+n] == A[s3:]:
+            return [s1+n-1, s2+n]
+        else:
+            return [-1, -1]
+```