valid paranthesis

Author: specialtactics

week3/valid-paranthesis-string.cpp

@@ -0,0 +1,71 @@
+// Probably bigger than it needs to be, but I'm feeling lazy !
+// Performance is also perfect so :shrug:
+
+class Solution {
+public:
+ bool checkValidString(string s) {
+ return checkForward(s) && checkBack(s); 
+ }
+ 
+ bool checkForward(string s) {
+ int opened = 0;
+ int wildcards = 0;
+ 
+ for (string::iterator it = s.begin(); it != s.end(); ++it) {
+ if (*it == '(') {
+ ++opened;
+ }
+ else if (*it == ')') {
+ --opened;
+ 
+ while (opened < 0 && wildcards > 0) {
+ ++opened;
+ --wildcards;
+ }
+ 
+ if (opened < 0) {
+ return false;
+ }
+ } else if (*it == '*') {
+ ++wildcards;
+ }
+ }
+ 
+ if (opened == 0 || abs(opened) <= wildcards) {
+ return true;
+ }
+ 
+ return false;
+ }
+ 
+ bool checkBack(string s) {
+ int closed = 0;
+ int wildcards = 0;
+ 
+ for (string::reverse_iterator it = s.rbegin(); it != s.rend(); ++it) {
+ if (*it == ')') {
+ ++closed;
+ }
+ else if (*it == '(') {
+ --closed;
+ 
+ while (closed < 0 && wildcards > 0) {
+ ++closed;
+ --wildcards;
+ }
+ 
+ if (closed < 0) {
+ return false;
+ }
+ } else if (*it == '*') {
+ ++wildcards;
+ }
+ }
+ 
+ if (closed == 0 || abs(closed) <= wildcards) {
+ return true;
+ }
+ 
+ return false;
+ }
+};