LeetCode65 Valid Number

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question

Validate if a given string is numeric.

Some examples:
“0” => true
” 0.1 ” => true
“abc” => false
“1 a” => false
“2e10” => true
Note: It is intended for the problem statement to be ambiguous. You should gather all requirements up front before implementing one.

thinking

通信软件课上学了FSM，看到这题的时候眼前一亮，但苦于不会敲C，幸好从http://blog.csdn.net/suwei19870312/article/details/12094233和https://github.com/fuwutu/LeetCode/blob/master/Valid%20Number.cpp上看到了相关解法。下图给出了部分状态转移例子（图太丑TNT）。

在交题的时候发现代码是有一点点bug的，导致测试案例有的没过，这是修改之后的版本（非原创）

bool isNumber(char* s) {    enum InputType        {            INVALID,    // 0            SPACE,      // 1            SIGN,       // 2            DIGIT,      // 3            DOT,        // 4            EXPONENT,   // 5            NUM_INPUTS  // 6        }inputType;        inputType= INVALID;        int transitionTable[][NUM_INPUTS] =        {            -1,  0,  3,  1,  2, -1,     // next states for state 0            -1,  8, -1,  1,  4,  5,     // next states for state 1            -1, -1, -1,  4, -1, -1,     // next states for state 2            -1, -1, -1,  1,  2, -1,     // next states for state 3            -1,  8, -1,  4, -1,  5,     // next states for state 4            -1, -1,  6,  7, -1, -1,     // next states for state 5            -1, -1, -1,  7, -1, -1,     // next states for state 6            -1,  8, -1,  7, -1, -1,     // next states for state 7            -1,  8, -1, -1, -1, -1,     // next states for state 8        };        int state = 0;        while (*s != '\0')        {            if (isspace(*s))                inputType = SPACE;            else if (*s == '+' || *s == '-')                inputType = SIGN;            else if (isdigit(*s))                inputType = DIGIT;            else if (*s == '.')                inputType = DOT;            else if (*s == 'e' || *s == 'E')                inputType = EXPONENT;            else inputType=INVALID; //修改            state = transitionTable[state][inputType];            if (state == -1)                return false;            else                ++s;        }        return state == 1 || state == 4 || state == 7 || state == 8;}

小结：enum的用法，transition[ ][NUM_INPUTS]数组的定义，以及最终状态的判断。
此思路值得借鉴。

try:   float(s.strip())   return Trueexcept:   return False

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