一、题目内容

二、题解

解法1：

思路

模拟

代码

public class Solution {
    /**
     * 
     * @param str string字符串 
     * @return int整型
     */
    public int atoi (String str) {
        // write code here
        if(str == null || str.isEmpty()){
            return 0;
        }
        str = str.trim();
        int sign = 1;
        int firstIndex = 0;
        int lastIndex = 0;
        char[] array = str.toCharArray();
        if(array[0] == '+'){
            firstIndex = 1;
        }else if(array[0] == '-'){
            firstIndex = 1;
            sign = -1;
        }
        for(int i = firstIndex;i<array.length;i++){
            if(array[i] == 'e'){
                break;
            }
            int curr = array[i] - '0';
            if(curr<0||curr>9){
                break;
            }
            lastIndex = i;
        }
        long c = 10;
        long res = array[lastIndex]-'0';
        for(int i = lastIndex-1;i>=firstIndex;i--){
            res+=(array[i]-'0')*c;
            c*=10;
        }
        res*=sign;
        if(res>Integer.MAX_VALUE){
            return Integer.MAX_VALUE;
        }else if(res<Integer.MIN_VALUE){
            return Integer.MIN_VALUE;
        }
        return (int)res;
    }
}