Runtime: 0 ms, faster than 100.00% of Rust online submissions for String to Integer (atoi).
Memory Usage: 2.4 MB, less than 100.00% of Rust online submissions for String to Integer (atoi).
Next challenges:
string-to-integer-atoi
思想：状态机
pub fn my_atoi(str: String) -> i32 {
let (i32_min, i32_max) = (-2_i64.pow(31), 2_i64.pow(31) - 1);
let mut num_match = false;
let mut result: i64 = 0;
let mut minus = false;
for ch in str.chars().into_iter() {
if !num_match {
match ch {
' ' => {}
'0'...'9' => {
num_match = true;
result = result * 10 + ch.to_digit(10).unwrap() as i64;
}
'-' => {
num_match = true;
minus = true;
}
'+' => {
num_match = true;
}
_ => return 0,
}
} else {
match ch {
'0'...'9' => {
result = result * 10 + ch.to_digit(10).unwrap() as i64;
if result > i32_max {
break;
}
}
_ => break,
}
}
}
result = if minus { -result } else { result };
if result > i32_max {
return i32_max as i32;
}
if result < i32_min {
println!("cccc:{}", result);
println!("cccc:{}", i32_min);
return i32_min as i32;
}
return result as i32;
}
