C++：杨辉三角、字符串相加

• 杨辉三角
• 字符串相加

class Solution {
public:
    vector> generate(int numRows) {
            vector> vv;
            vv.resize(numRows);
            for(size_t i = 0; i
                /0层开1个空间 1 2 
                vv[i].resize(i+1,0);
                /每一层的头尾初始化成1
                vv[i][0]=1;
                vv[i][vv[i].size()-1] =1;
            }
            / i j 等于上一层 i-1 j-1 + i-1 j 
            for(int i =0;i
                for(int j =0;j
                    if(vv[i][j]==0)
                    {
                       vv[i][j]= vv[i-1][j]+vv[i-1][j-1];
                    }
                }
            }
            return vv;
    }
};

class Solution {
public:
    string addStrings(string num1, string num2) {
			int end1 = num1.size()-1;
			 int end2 = num2.size()-1;
			 int value1 = 0, value2 = 0, next = 0;
			string addret;
 			while(end1 >= 0 || end2 >= 0)
			 {
			 /先转成数字
				 if(end1 >= 0)
				 value1 = num1[end1--]-'0';
				 else
				 value1 = 0;
 
				 if(end2 >= 0)
				 value2 = num2[end2--]-'0';
				 else
 			     alue2 = 0;
 					
				 int valueret = value1 + value2 + next; /求和
				 if(valueret > 9)
				 {
					 next = 1;
					 valueret -= 10;
				 }
				 else
				 {
					 next = 0;
				 }
				addret += (valueret+'0');/赋值给对象	
    		}
    		if(next == 1) /处理最后的进位1
			 {
				 addret += '1';
			 }
			 reverse(addret.begin(), addret.end());/算法逆置
			 return addret;
};