python dictionary

19_HashMap/01. Continuous Subarray Sum.py

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+# https://leetcode.com/problems/continuous-subarray-sum/
+
+class Solution:
+    def checkSubarraySum(self, nums: List[int], k: int) -> bool:
+        sumIndexDic = {0 : -1}    # nums = [14, 7]; k = 7
+        curSum = 0
+
+        for i in range(len(nums)):
+            curSum += nums[i]
+            curSum = curSum % k
+
+            if curSum in sumIndexDic:
+                if i - sumIndexDic[curSum] >= 2: 
+                    return True
+            else:
+                sumIndexDic[curSum] = i
+
+        return False

19_HashMap/02. Subarray Sums Divisible by K.py

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+# https://leetcode.com/problems/subarray-sums-divisible-by-k/
+# https://www.youtube.com/watch?v=QM0klnvTQzk
+
+class Solution:
+    def subarraysDivByK(self, nums: List[int], k: int) -> int:
+        # Use COncept of 523. Continuous Subarray Sum
+
+        ans = 0
+        remainderCountDic = {0 : 1}
+        curSum = 0
+
+        for i in range(len(nums)):
+            curSum += nums[i]
+
+            if curSum < 0: curSum += k
+
+            curSum = curSum 
+
+            if curSum in remainderCountDic:
+                ans += remainderCountDic[curSum]
+                remainderCountDic[curSum] += 1
+            else:
+                remainderCountDic[curSum] = 1
+
+        return ans