🚀 27-Jul-2020

Author: sureshmangs

competitive programming/leetcode/2020-July-Challenge/Day-26-Add Digits.cpp

@@ -0,0 +1,59 @@
+Given a non-negative integer num, repeatedly add all its digits until the result has only one digit.
+
+Example:
+
+Input: 38
+Output: 2
+Explanation: The process is like: 3 + 8 = 11, 1 + 1 = 2.
+             Since 2 has only one digit, return it.
+Follow up:
+Could you do it without any loop/recursion in O(1) runtime?
+
+   Hide Hint #1
+A naive implementation of the above process is trivial. Could you come up with other methods?
+   Hide Hint #2
+What are all the possible results?
+   Hide Hint #3
+How do they occur, periodically or randomly?
+   Hide Hint #4
+You may find this Wikipedia article useful.
+
+
+
+
+
+
+
+
+
+class Solution {
+public:
+    int addDigits(int num) {
+           int digitalRoot = 0;
+            while (num > 0) {
+                digitalRoot += num % 10;
+                num = num / 10;
+
+                if (num == 0 && digitalRoot > 9) {
+                    num = digitalRoot;
+                    digitalRoot = 0;
+                }
+            }
+            return digitalRoot;
+    }
+};
+
+
+
+
+
+
+
+class Solution {
+public:
+    int addDigits(int num) {
+        if (num == 0) return 0;
+        if (num % 9 == 0) return 9;
+        return num % 9;
+    }
+};

competitive programming/leetcode/258. Add Digits.cpp

@@ -0,0 +1,51 @@
+Given a non-negative integer num, repeatedly add all its digits until the result has only one digit.
+
+Example:
+
+Input: 38
+Output: 2
+Explanation: The process is like: 3 + 8 = 11, 1 + 1 = 2.
+             Since 2 has only one digit, return it.
+Follow up:
+Could you do it without any loop/recursion in O(1) runtime?
+
+
+
+
+
+
+
+
+
+
+class Solution {
+public:
+    int addDigits(int num) {
+           int digitalRoot = 0;
+            while (num > 0) {
+                digitalRoot += num % 10;
+                num = num / 10;
+
+                if (num == 0 && digitalRoot > 9) {
+                    num = digitalRoot;
+                    digitalRoot = 0;
+                }
+            }
+            return digitalRoot;
+    }
+};
+
+
+
+
+
+
+
+class Solution {
+public:
+    int addDigits(int num) {
+        if (num == 0) return 0;
+        if (num % 9 == 0) return 9;
+        return num % 9;
+    }
+};