Leetcode-evaluate reverse Polish notation [AC source code]

1 package COM. LW. leet2; 2 3/** 4 * @ classname: solution 5 * @ Description: 6 * evaluate the value of an arithmetic expression in reverse Polish notation. 7 * Valid operators are + ,-,*,/. each operand may be an integer or another expression. 8*9 * some examples: 10 * ["2", "1", "+", "3", "*"]-> (2 + 1) * 3)-> 911 * ["4", "13", "5", "/", "+"]-> (4 + (13/5 )) -> 612*13 * @ author liuwei14 * @ date August 16, 2014 * @ Mail [email protected] 16 */17 public class solution {18 19 private Boolean isted (string S) {20 if (S. equals ("+") {21 return true; 22} 23 if (S. equals ("-") {24 return true; 25} 26 if (S. equals ("*") {27 return true; 28} 29 If (S. equals ("/") {30 return true; 31} 32 return false; 33} 34 35 private string getoperres (string num1, string num2, string success) {36 IF (response. equals ("+") {37 return integer. valueof (num1) + integer. valueof (num2) + ""; 38} 39 else if (response. equals ("-") {40 return integer. valueof (num1)-integer. valueof (num2) + ""; 41} 42 else if (else. equals ("*") {43 return integer. valueof (num1) * integer. valueof (num2) + ""; 44} 45 else {46 Return integer. valueof (num1)/integer. valueof (num2) + ""; 47} 48} 49 50 public int evalrpn (string [] tokens) {51 string [] resarr = new string [tokens. length]; 52 int Index = 0; 53 for (INT I = 0; I <tokens. length; I ++) {54 if (isoper (tokens [I]) {55 string num1 = resarr [index-1]; 56 string num2 = resarr [index-2]; 57 resarr [index-2] = getoperres (num2, num1, tokens [I]); 58 index --; 59} 60 else {61 resarr [Index] = tokens [I]; 62 index ++; 63} 64} 65 return integer. valueof (resarr [0]); 66} 67 68 public static void main (string [] ARGs) {69 solution S = new solution (); 70 // string [] tokens = {"4", "13", "5", "/", "+ "}; 71 string [] tokens = {"2", "1", "+"}; 72 system. out. println (S. evalrpn (tokens); 73} 74}