【leetcode】Valid Number
2013-04-21 23:50
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Question :
Validate if a given string is numeric.Some examples:
Note: It is intended for the problem statement to be ambiguous. You should gather all requirements up front before implementing one.Anwser 1 :
Anwser 2 :
参考推荐:
Valid Number
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.Anwser 1 :
class Solution { public: bool isNumber(const char *s) { // Start typing your C/C++ solution below // DO NOT write int main() function if (s == NULL) return false; while(isspace(*s)) s++; if (*s == '+' || *s == '-') s++; bool eAppear = false; bool dotAppear = false; bool firstPart = false; bool secondPart = false; bool spaceAppear = false; while(*s != '\0') { if (*s == '.') { if (dotAppear || eAppear || spaceAppear) return false; else dotAppear = true; } else if (*s == 'e' || *s == 'E') { if (eAppear || !firstPart || spaceAppear) return false; else eAppear = true; } else if (isdigit(*s)) { if (spaceAppear) return false; if (!eAppear) firstPart = true; else secondPart = true; } else if (*s == '+' || *s == '-') // behind of e/E { if (spaceAppear) return false; if (!eAppear || !(*(s-1) == 'e' || *(s-1) == 'E')) return false; } else if (isspace(*s)) spaceAppear = true; else return false; s++; } if (!firstPart) { return false; } else if (eAppear && !secondPart) { return false; } return true; } };
Anwser 2 :
class Solution { public: bool isNumber(const char *s) { // Start typing your C/C++ solution below // DO NOT write int main() function int mat[11][7] = { 0 ,0 ,0 ,0 ,0 ,0 ,0, // false 0 ,2 ,3 ,0 ,1 ,4 ,0, // 1 0 ,2 ,5 ,6 ,9 ,0 ,10, // 2 0 ,5 ,0 ,0 ,0 ,0 ,0, // 3 0 ,2 ,3 ,0 ,0 ,0 ,0, // 4 0 ,5 ,0 ,6 ,9 ,0 ,10, // 5 0 ,7 ,0 ,0 ,0 ,8 ,0, // 6 0 ,7 ,0 ,0 ,9 ,0 ,10, // 7 0 ,7 ,0 ,0 ,0 ,0 ,0, // 8 0 ,0 ,0 ,0 ,9 ,0 ,10, // 9 10,10,10,10,10,10,10 // 10 }; int i = 0; int stat = 1; while(s[i] != '\0') { int type = 0; if(s[i] >= '0' && s[i] <= '9') type = 1; else if(s[i] == '.') type = 2; else if(s[i] == 'e') type = 3; else if(s[i] == ' ') type = 4; else if(s[i] == '+' || s[i] == '-') type = 5; if(stat == 0) return false; stat = mat[stat][type]; i++; } stat = mat[stat][6]; if(stat == 10) { return true; } return false; } };
参考推荐:
Valid Number
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