string--OJ1

链接: 例一

链接: 例er

class Solution {
public:int myAtoi(string str) {int sign = 1;int ret=0;int i=0;while(str[i]==' '){i++;}if(str[i]=='+'||str[i]=='-'){if(str[i]=='-')sign*=-1;i++;}while(str[i]>='0'&&str[i]<='9'){int r=str[i] - '0';if(ret>INT_MAX/10||(ret==INT_MAX/10&&r>7)){return sign>0?INT_MAX:INT_MIN;}ret = ret * 10+r ;i++;}return ret*sign;}
};

class Solution {
public:string addStrings(string num1, string num2) {int sm=0,l1=num1.size(),l2=num2.size();string ans=""; while(l1||l2||sm){if(l1)sm+=num1[--l1]-'0';if(l2)sm+=num2[--l2]-'0';ans=char('0'+sm%10)+ans;sm/=10;}return ans;}
};