Numbers in English are written down in the following way (only numbers less than 109 are considered). Number abc,def,ghi is written as "[abc] million [def] thousand [ghi]". Here "[xyz] " means the written down number xyz .
In the written down number the part "[abc] million" is omitted if abc = 0 , "[def] thousand" is omitted if def = 0 , and "[ghi] " is omitted if ghi = 0 . If the whole number is equal to 0 it is written down as "zero". Note that words "million" and "thousand" are singular even if the number of millions or thousands respectively is greater than one.
Numbers under one thousand are written down in the following way. The number xyz is written as "[x] hundred and [yz] ”. ( If yz = 0 it should be only “[x] hundred”. Otherwise if y = 0 it should be only “[x] hundred and [z]”.) Here "[x] hundred and" is omitted if x = 0 . Note that "hundred" is also always singular.
Numbers under 20 are written down as "zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine", "ten", "eleven", "twelve", "thirteen", "fourteen", "fifteen", "sixteen", "seventeen", "eighteen", and "nineteen" respectively. Numbers from 20 to 99 are written down in the following way. Number xy is written as "[x0] [y] ", and numbers divisible by ten are written as "twenty", "thirty", "forty", "fifty", "sixty", "seventy", "eighty", and "ninety" respectively.
For example, number 987,654,312 is written down as "nine hundred and eighty seven million six hundred and fifty four thousand three hundred and twelve", number 100,000,037 as "one hundred million thirty seven", number 1,000 as "one thousand". Note that "one" is never omitted for millions, thousands and hundreds.
Give you the written down words of a number, please give out the original number.
Input
Standard input will contain multiple test cases. The first line of the input is a single integer T (1 <= T <= 1900) which is the number of test cases. It will be followed by T consecutive test cases.
Each test case contains only one line consisting of a sequence of English words representing a number.
Output
For each line of the English words output the corresponding integer in a single line. You can assume that the integer is smaller than 109.
Sample Input
3 one eleven one hundred and two
Sample Output
1 11 102
贴上题目的地址：
http://acm.zju.edu.cn/onlinejudge/showProblem.do?problemCode=2971
先说题目吧，这玩意就是一个在线翻译的东东，就是把英文表示的数字转换成阿拉伯数字。
然后再说解题的思路：
1.数字，比如1，2，3，11，30这种的，肯定没办法通过计算来得到，只能switch case，这些就是最小的基本单位。
2.然后是 32这种由30 + 2 就可以得出
3.下来就是hundred这些有单位的（不是说没有十位个位哈，只是十位个位没有单独的字符串来表示），one hundred就是 1*100
4.上面的数都比较特殊，也是基本单位，然后就是推广了。
three hundred an twelve 从hundred单位这里分开，整个数的结果就等于 L*单位+R 就是左边的数值乘上单位，然后加上单位右面的数字。
然后对L，R的值，又可以递归的调用这个方法，得出它的值，直到单位小于100的，就直接把数字相加（本质上就是L*1+R）
懂了这个就好办了，直接贴代码吧，个人对代码的要求没写那么精炼，确实有待改进：
1 import java.util.Scanner; 2 public class Main { 3 public static void main(String[] args) { 4 //String key="nine hundred and eighty seven million six hundred and fifty four thousand three hundred and twelve"; 5 Scanner sc = new Scanner(System.in); 6 int T=sc.nextInt(); 7 sc.nextLine(); 8 while(T>0){ 9 String input; 10 input=sc.nextLine(); 11 input.toLowerCase(); 12 String []word = input.split(" "); 13 14 long dan[]=new long[word.length+1]; 15 //获取最大的单位 16 //初始化 17 for (int i = 0; i < word.length; i++) { 18 String key = word[i]; 19 switch (key) { 20 case "hundred": 21 dan[i]=100; 22 break; 23 case "thousand": 24 dan[i]=1000; 25 break; 26 case "million": 27 dan[i]=1000000; 28 break; 29 default: 30 dan[i]=0; 31 break; 32 }//switch 33 }//for 34 long result = getResult(word, dan, 0, word.length); 35 System.out.println(result); 36 T--; 37 } 38 } 39 40 //first 包含，last不包含 41 public static long getResult(String word[],long dan[],int first,int last){ 42 long res=0; 43 long max=1; 44 int maxnum=0; 45 46 //找到单位最大的那个 47 for (int i = first; i < last; i++) { 48 if(dan[i]>max){ 49 max =dan[i]; 50 maxnum=i; 51 } 52 } 53 long left=0; 54 long right=0; 55 int num=0; 56 57 if(max>1){ 58 //这里递归调用 59 left=getResult(word,dan,first,maxnum); 60 61 right= getResult(word, dan, maxnum+1, last); 62 63 res=left*max+right; 64 65 }else{ 66 67 for (int i = first; i < last; i++) { 68 // 69 String key= word[i]; 70 switch (key) { 71 case "zero": 72 num += 0; 73 break; 74 case "one": 75 num += 1; 76 break; 77 case "two": 78 num += 2; 79 break; 80 case "three": 81 num += 3; 82 break; 83 case "four": 84 num += 4; 85 break; 86 case "five": 87 num += 5; 88 break; 89 case "six": 90 num += 6; 91 break; 92 case "seven": 93 num += 7; 94 break; 95 case "eight": 96 num += 8; 97 break; 98 case "nine": 99 num += 9; 100 break; 101 case "ten": 102 num += 10; 103 break; 104 case "eleven": 105 num += 11; 106 break; 107 case "twelve": 108 num += 12; 109 break; 110 case "thirteen": 111 num += 13; 112 break; 113 case "fourteen": 114 num += 14; 115 break; 116 case "fifteen": 117 num += 15; 118 break; 119 case "sixteen": 120 num += 16; 121 break; 122 case "seventeen": 123 num += 17; 124 break; 125 case "eighteen": 126 num += 18; 127 break; 128 case "nineteen": 129 num += 19; 130 break; 131 case "twenty": 132 num += 20; 133 break; 134 case "thirty": 135 num += 30; 136 break; 137 case "forty": 138 num += 40; 139 break; 140 case "fifty": 141 num += 50; 142 break; 143 case "sixty": 144 num += 60; 145 break; 146 case "seventy": 147 num += 70; 148 break; 149 case "eighty": 150 num += 80; 151 break; 152 case "ninety": 153 num += 90; 154 break; 155 case "hundred": 156 break; 157 case "thousand": 158 break; 159 case "million": 160 break; 161 case "and": 162 break; 163 default: 164 break; 165 } 166 }//for 167 res = num; 168 } 169 170 return res; 171 } 172 } 173
测试结果如下，直接通过了。
明显的能感觉到java程序的效率和c/c++真没法比。