[Leetcode] Valid Parentheses
阿新 • • 發佈:2019-04-09
div image emp true 技術 () rar ack color
字串是不是由合法的括號組組成
public class Solution { /// <summary> /// ‘(‘ 40, ‘)‘41, ‘{‘123, ‘}‘125, ‘[‘91 and ‘]‘93 /// </summary> /// <param name="s"></param> /// <returns></returns> public bool IsValid(string s) {//空字串也合法 if (string.IsNullOrEmpty(s)) return true; //括號一定是兩兩成對 排除字元陣列奇數個 if (s.Length % 2 > 0) return false; char[] arr = s.ToCharArray(); //兩個直接判斷 if (s.Length == 2) {return ((((int)arr[1] - (int)arr[0] == 2) || (int)arr[1] - (int)arr[0] == 1)); } //使用stack 如果有剩下未pop的 就是非法 Stack stack = new Stack(); char poper = ‘0‘; char current = ‘0‘; bool result = true; for(int i =0; i < arr.Length; i++) { current= arr[i]; if (current == ‘(‘ || current == ‘[‘ || current == ‘{‘) { stack.Push(arr[i]); continue; } else //(current == ‘)‘ || current == ‘]‘ || current == ‘}‘) { //‘)‘的數量多於‘(‘ 直接false if(stack.Count == 0) { result = false; break; } poper = (char)stack.Pop(); } //找到一個不是成對的馬上false if((((current - poper == 2) || current - poper == 1)) == false) { result = false; break; } } stack = null; if (result == true) { return stack.Count == 0; } return result; } }
[Leetcode] Valid Parentheses