Home » Source Code » Leetcode the reference source code (Java) » EvaluateReversePolishNotation.java

EvaluateReversePolishNotation.java ( File view )

  • By issaczr 2014-10-24
  • View(s):52
  • Download(s):0
  • Point(s): 1
			// Author:   Li Long, 1988lilong@163.com
// Date:     Apr 18, 2014
// Source:   http://oj.leetcode.com/problems/evaluate-reverse-polish-notation/
// Analysis: http://blog.csdn.net/lilong_dream/article/details/20204273

// Evaluate the value of an arithmetic expression in Reverse Polish Notation.
// Valid operators are +, -, *, /. Each operand may be an integer or another expression.
// Some examples:
// ["2", "1", "+", "3", "*"] -> ((2 + 1) * 3) -> 9
// ["4", "13", "5", "/", "+"] -> (4 + (13 / 5)) -> 6

import java.util.Stack;

public class EvaluateReversePolishNotation {

	public int evalRPN(String[] tokens) {

		String operators = "+-*/";
		Stack<String> s = new Stack<String>();

		for (String str : tokens) {

			if (operators.contains(str)) {

				int num2 = Integer.valueOf(s.pop());
				int num1 = Integer.valueOf(s.pop());

				int index = operators.indexOf(str);
				switch (index) {

				case 0:
					s.push(String.valueOf(num1 + num2));
					break;
				case 1:
					s.push(String.valueOf(num1 - num2));
					break;
				case 2:
					s.push(String.valueOf(num1 * num2));
					break;
				case 3:
					s.push(String.valueOf(num1 / num2));
					break;
				
}
			
} else {

				s.push(str);
			
}
		
}

		return Integer.valueOf(s.pop());
	
}

	public static void main(String[] args) {

		String[] s = {
 "10", "6", "9", "3", "+", "-11", "*", "/", "*", "17",
				"+", "5", "+" 
};
		EvaluateReversePolishNotation slt = new EvaluateReversePolishNotation();
		System.out.println(slt.evalRPN(s));
	
}

}			
...
Expand> <Close

Want complete source code? Download it here

Point(s): 1

Download
0 lines left, continue to read
Sponsored links

File list

Tips: You can preview the content of files by clicking file names^_^
Name Size Date
01.97 kB
01.97 kB
AddBinary.java1.58 kB2014-05-09 03:48
AddTwoNumbers.java2.54 kB2014-05-09 03:48
BinaryTreePreorderTraversal.java1.91 kB2014-05-09 03:48
ClimbingStairs.java811.00 B2014-05-09 03:48
EvaluateReversePolishNotation.java1.51 kB2014-05-09 03:48
GenerateParentheses.java1.15 kB2014-05-09 03:48
ImplementStrStr.java1.00 kB2014-05-09 03:48
InsertionSortList.java1.64 kB2014-05-09 03:48
IntegerToRoman.java923.00 B2014-05-09 03:48
LengthOfLastWord.java1.11 kB2014-05-09 03:48
LinkedListCycle.java1.32 kB2014-05-09 03:48
LinkedListCycleII.java1.28 kB2014-05-09 03:48
LongestCommonPrefix.java916.00 B2014-05-09 03:48
LongestSubstring.java1.79 kB2014-05-09 03:48
MaximumSubarray.java1.10 kB2014-05-09 03:48
MedianOfTwoSortedArrays.java1.68 kB2014-05-09 03:48
MergeSortedArray.java1.12 kB2014-05-09 03:48
MergeTwoSortedLists.java1.84 kB2014-05-09 03:48
MinimumPathSum.java1.19 kB2014-05-09 03:48
PathSum.java1.67 kB2014-05-09 03:48
PlusOne.java1.06 kB2014-05-09 03:48
Powxn.java712.00 B2014-05-09 03:48
RemoveDuplicatesFromSortedList.java1.48 kB2014-05-09 03:48
RemoveDuplicatesfromSortedArray.java1.30 kB2014-05-09 03:48
RemoveElement.java885.00 B2014-05-09 03:48
RemoveNthNodeFromEnd.java1.70 kB2014-05-09 03:48
ReverseInteger.java936.00 B2014-05-09 03:48
RotateList.java1.53 kB2014-05-09 03:48
SameTree.java1.15 kB2014-05-09 03:48
SearchForARange.java1.37 kB2014-05-09 03:48
SearchInRotatedSortedArray.java1.27 kB2014-05-09 03:48
SearchInsertPosition.java1.09 kB2014-05-09 03:48
SetMatrixZeroes.java1.95 kB2014-05-09 03:48
SingleNumber.java935.00 B2014-05-09 03:48
SortList.java1.75 kB2014-05-09 03:48
Sqrt.java907.00 B2014-05-09 03:48
StringToInteger_atoi.java1.46 kB2014-05-09 03:48
Sum3.java1.76 kB2014-05-09 03:48
TwoSum.java2.33 kB2014-05-09 03:48
UniqueBinarySearchTrees.java1.01 kB2014-05-09 03:48
UniquePaths.java976.00 B2014-05-09 03:48
UniquePathsII.java1.84 kB2014-05-09 03:48
ValidParentheses.java1.23 kB2014-05-09 03:48
ValidateBinarySearchTree.java1.44 kB2014-05-09 03:48
...
Sponsored links

EvaluateReversePolishNotation.java (35.66 kB)

Need 1 point
Your Point(s)

Your Point isn't enough.

Get point immediately by PayPal

More(Debit card / Credit card / PayPal Credit / Online Banking)

Submit your source codes. Get more point

LOGIN

Don't have an account? Register now
Need any help?
Mail to: support@codeforge.com

切换到中文版?

CodeForge Chinese Version
CodeForge English Version

Where are you going?

^_^"Oops ...

Sorry!This guy is mysterious, its blog hasn't been opened, try another, please!
OK

Warm tip!

CodeForge to FavoriteFavorite by Ctrl+D