code
class Solution {
public:
/**
* @param str: A string
* @return An integer
*/
int atoi(string str) {
// write your code here
str = eraseSpace(str);
int size=str.size();
if(size <= 0)
return 0;
if(str[0]<='9' && str[0]>='0') {
int num=str[0]-'0', i, dec=str[0]-'0';
for(i=1; i<size; i++) {
if(str[i]<='9' && str[i]>='0') {
dec = num;
num = num * 10;
if(isCrossBorder(num, dec))
return 2147483647;
dec = num;
num += str[i]-'0';
if(isCrossBorder(num, dec))
return 2147483647;
}
else {
return num;
}
}
return num;
}
else if(str[0] == '+') {
int num=0, i, dec=0;
for(i=1; i<size; i++) {
if(str[i]<='9' && str[i]>='0') {
dec = num;
num = num * 10;
if(isCrossBorder(num, dec))
return 2147483647;
dec = num;
num += str[i]-'0';
if(isCrossBorder(num, dec))
return 2147483647;
}
else {
return num;
}
}
return num;
}
else if(str[0] == '-') {
int num=0, i, dec=0;
for(i=1; i<size; i++) {
if(str[i]<='9' && str[i]>='0') {
dec = num;
num = num * 10;
if(isCrossBorder(num, dec))
return -2147483648;
dec = num;
num += str[i]-'0';
if(isCrossBorder(num, dec))
return -2147483648;
}
else {
return num*-1;
}
}
return num*-1;
}
else {
return 0;
}
}
bool isCrossBorder(int num1, int num2) {
if(num1 < num2)
return true;
return false;
}
string eraseSpace(string str) {
int size=str.size(),i=0,mark=0;
string result;
for(i=0; i<size; i++) {
if(str[i]==' ' && mark==0) {
continue;
}
else if(str[i]!=' ' && mark==0) {
mark = 1;
result += str[i];
}
else if(str[i]!=' ' && mark==1) {
mark = 1;
result += str[i];
}
else if(str[i]==' ' && mark==1) {
break;
}
}
return result;
}
};