11 该题主要是从两端向中间，每次移动矮的一边，直到两者相遇结束。还有，题目提示的意思是不能倾斜，我开始的时候理解错了，连续提交多次失败才明白
class Solution {
public:
int maxArea(vector<int> &height) {
long long sum=0,tmp=0;
int len=height.size();
if(len==1)return 0;
int tmp1=0,tm2=0;
int left=0,right=len-1;
while(left<=right){
tmp=(right-left)*min(height[right],height[left]);
if(height[right]<height[left]){
right--;
}
else left++;
if(tmp>sum)sum=tmp;
}
return sum;
}
};
12 该题只是简单的替换，列举候循环即可
string myf(int x,int num){
string ss="IVXLCDM";
string s="";
for(int i=0;i<num;i++)
s+=ss[x];
return s;
}
class Solution {
public:
string intToRoman(int num) {
string answer="";
int x=num;
int k=1000;num=0;
while(x){
if(x/k){answer+=myf(6-num,x/k);x=x%k;}
if(x<=0)break;
if(x>=k*(10-1)/10)
{answer+=myf(4-num,1);answer+=myf(6-num,1);x-=k*9/10;}
if(x<=0)break;
if(x>=(k/2))
{answer+=myf(5-num,1);x-=k*5/10;}
if(x<=0)break;
if(x>=(4*k/10))
{answer+=myf(5-num-1,1);;answer+=myf(5-num,1);x-=(4*k/10);}
if(x<=0)break;
k=k/10;
num+=2;
}
return answer;
}
};