added cses

leetcode/lc1784.cpp

@@ -0,0 +1,51 @@
+class Solution{
+    public: 
+        bool checkOnesSegment(string s){
+            return s.find("01") == string::npos;
+        }
+};
+
+//TC: o(n), SC:o(1)
+
+
+//npos is a special cpp constant stands for "no position" which is essentially not found value, (size_t(-1)) returned by find() and such functions
+
+/*
+find()
+- finds FIRST occurrence of substring
+
+Example:
+string s = "banana";
+s.find("na") -> 2
+
+--------------------------------
+
+rfind()
+- finds LAST occurrence of substring
+
+Example:
+string s = "banana";
+s.rfind("na") -> 4
+
+--------------------------------
+
+find_first_of()
+- finds first character that matches
+  ANY char from a given set
+
+Example:
+string s = "hello";
+s.find_first_of("aeiou") -> 1  // 'e'
+
+--------------------------------
+
+find_last_of()
+- finds last character that matches
+  ANY char from a given set
+
+Example:
+string s = "hello";
+s.find_last_of("aeiou") -> 4  // 'o'
+
+--------------------------------
+*/