Find the law (112,358 ...), the output of 50 is much

Problem-solving ideas

• Law after a number of two numbers before and

Reference Solution

• Violence can be calculated directly

• Note that the first number exceeds 50 represents the range of the int (2 ^ 31--1 = 2147483647), need long long,

  #include <iostream>
  #include <vector>
  
  using namespace std;
  
  int main()
  {
      vector<long long> arr={1, 1};
      for(int i = 2; i < 50; i++){
          arr.push_back(arr[i-2] + arr[i-1]);  // 注意vector可以用索引访问内容，但是不可以用索引修改内容！！
      }
      cout << arr[arr.size()-1] << endl;  //size()返回的是vector中最后一个元素的下一个位置
      return 0;
  }