Q15 Code commit

Microsoft/Q15NumberofSubstringsContainingAllThre Characters.cpp

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+1358. Number of Substrings Containing All Three Characters
+// Given a string s consisting only of characters a, b and c.
+
+// Return the number of substrings containing at least one occurrence of all these characters a, b and c.
+// Example 1:
+
+// Input: s = "abcabc"
+// Output: 10
+// Explanation: The substrings containing at least one occurrence of the characters a, b and c are "abc", "abca", "abcab", "abcabc", "bca", "bcab", "bcabc", "cab", "cabc" and "abc" (again). 
+// Example 2:
+
+// Input: s = "aaacb"
+// Output: 3
+// Explanation: The substrings containing at least one occurrence of the characters a, b and c are "aaacb", "aacb" and "acb". 
+// Example 3:
+
+// Input: s = "abc"
+// Output: 1
+//Used Sliding Window Approach
+
+class Solution {
+public:
+    int numberOfSubstrings(string s) {
+        int left=0, right=0, count=0, n= s.size()-1 ;
+        unordered_map<char, int> mp ;
+
+        while(right < s.size()){
+            mp[s[right]]++ ;
+
+            while(mp['a']  &&  mp['b']  &&  mp['c']){
+                count += 1+ (n - right) ;
+
+                mp[s[left]]-- ;
+                left++ ;
+            }
+
+            right++ ;
+        }
+
+        return count ;
+    }
+};