classSolution{publicintmyAtoi(String str){char[] arr = str.toCharArray();int len = arr.length;int index =0;long ans =0;int symbol =0;boolean jud =true;while(index < len && arr[index]==' '){// 去掉前导空格
index++;}while(jud && index < len){if(arr[index]>=48&& arr[index]<=57){//if numif(symbol ==0){
symbol =1;}
ans = ans *10+(int) arr[index]-48;}elseif(arr[index]<48|| arr[index]>57){//if not numif(ans ==0&& symbol ==0){if(arr[index]=='+'){
symbol =1;}elseif(arr[index]=='-'){
symbol =-1;}else{
jud =false;}}else{
jud =false;}}if(ans > Integer.MAX_VALUE){//if >maxiumif(symbol ==1){
ans = Integer.MAX_VALUE;}elseif(symbol ==-1){
ans = Integer.MIN_VALUE;
symbol =1;}
jud =false;}
index++;}return(int)(symbol * ans);}}