有限状态机求解字符串匹配问题

问题描述：

请实现一个函数用来判断字符串是否表示数值（包括整数和小数）。例如，字符串"+100","5e2","-123","3.1416"和"-1E-16"都表示数值。 但是"12e","1a3.14","1.2.3","+-5"和"12e+4.3"都不是。

class Solution {public:    char arr[10] = "+-n.ne+-n";    int turn[10][9] = {       //+  -  n  .  n  e  +  -  n        {1, 1, 1, 0, 0, 0, 0, 0, 0},    // # start        {0, 0, 1, 1, 0, 0, 0, 0, 0},    // +        {0, 0, 1, 1, 0, 0, 0, 0, 0},    // -        {0, 0, 1, 1, 0, 1, 0, 0, 0},    // n        {0, 0, 0, 0, 1, 0, 0, 0, 0},    // .        {0, 0, 0, 0, 1, 1, 0, 0, 0},    // n        {0, 0, 0, 0, 0, 0, 1, 1, 1},    // e        {0, 0, 0, 0, 0, 0, 0, 0, 1},    // +        {0, 0, 0, 0, 0, 0, 0, 0, 1},    // -        {0, 0, 0, 0, 0, 0, 0, 0, 1}     // n    };    bool isNumeric(char* string) {        int cur = 0;        for(int j, i = 0; string[i]; i++) {            for(j = 0; j < 9; j++) {                if(turn[cur][j]) {                    if(('0' <= string[i] && string[i] <= '9' && arr[j] == 'n') ||                        (string[i] == 'E' && arr[j] == 'e')||                        string[i] == arr[j]) {                        cur = j + 1;                        break;                    }                }            }            if(j == 9) return false;        }        if(cur == 3 || cur == 4 || cur == 5 || cur == 9)           return true;        return false;    }};