突击刷题： atoi, string to integer

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class Solution { public: /** * @param str: A string * @return An integer */ int atoi(string str) { // write your code here const char* s=str.c_str(); int result=0; static int CHECK= INT_MAX/10; static int MAX_CHECK = INT_MAX%10; static int MIN_CHECK= MAX_CHECK+1; bool sign=false; while(isspace(*s)) s++; if (*s=='+'||*s=='-'){ if (*s=='-') sign=true; s++; } while(isdigit(*s)){ int val=*s-'0'; if (sign && (result>CHECK || result == CHECK && val>=MIN_CHECK)) return INT_MIN; if (!sign && (result>CHECK || result == CHECK && val>=MAX_CHECK)) return INT_MAX; result=10*result+val; s++; } return sign?-result:result; } };