Roman to Integer

Given a Roman numeral, convert it to an integer.

Input is guaranteed to being within the range from 1 to 3999

Roman Numeral Counting Method:

Basic characters	I	V	X	L	C	D	M
The corresponding Arabic numerals are expressed as	1	5	10	50	100	500	1000

1, the same number ligatures, the number is equal to the number of the sum of these numbers, such as: ⅲ= 3, 2, the small number on the right side of the large number, the number represented is equal to the number of these numbers, such as: ⅷ= 8;ⅻ= 12;3, small numbers, (limited to Ⅰ, X and C) on the left of the large numbers The number represented is equal to the number of the number of large number reduction, such as: ⅳ= 4;ⅸ= 9;4, normal use, the number of ligatures can not be repeated more than three times. (Exception of four O'Clock "IIII" on the Dial) 5. Draw a horizontal line over a number to indicate that the number is enlarged by 1000 times times. Rules: 1, the basic number of Ⅰ, X, C of any one, the number of their own use, or placed on the right of the large number of the number of the composition, not more than three; on the left side of the large number can only use one. 2, can not be the basic number of V, L, D any one as a decimal place on the left of the large number of the method of subtracting the number of methods; 3, V and X left small numbers can only be used Ⅰ. The small numbers on the left of 4, L and C can only be used with X. The small numbers on the left of 5, D and M can only be used in C. (from Baidu Encyclopedia: http://baike.baidu.com/link?url=44M1P1d9WnPI7fucoCuM4FPX5d5ZJogqNHnxxtVTtbgxcqGjKWR8i9bBYakM3DH5ug1wW7 _YLJ0J-5FOVGK0EA)

#include <string.h> #include <stdio.h>int ctoi (char c) {    switch (c) {case        ' I ': return 1;        Case ' V ': return 5;        Case ' X ': return ten;        Case ' L ': return;        Case ' C ': return;        Case ' D ': return;        Case ' M ': return;    }} int Romantoint (char *s) {    int data=0;    int i,j;    for (i=0;s[i+1]!= '; i++) {        if (Ctoi (S[i]) >=ctoi (s[i+1])) Data=data+ctoi (S[i]);        else Data=data-ctoi (S[i]);    }    if (s[i+1]== ') Data=data+ctoi (S[i]);    return data;} void Main () {    printf ("%d\n", Romantoint ("XCIX"));}

Roman to Integer