[LeetCode] Range Sum Query - Immutable 区域和检索 - 不可变

1. 这段时间主要做DP的题目
2. 以后做题的目标，做一道会一道，举一反三。
   #include
   #include
   using namespace std;
   class RangeSumQueryImmutable
   {
   public:
   RangeSumQueryImmutable(vector &num)
   {
   dp = num;
   for (int i = 1; i < num.size(); i++)
   {
   dp[i] = dp[i - 1] + dp[i];
   }
   }
   int sumRange(int i, int j)
   {
   return i == 0 ? dp[j] : dp[j] - dp[i - 1];
   }
   private:
   vector dp;
   };
   int maxT(int a, int b)
   {
   if (a > b)
   {
   return a;
   }
   return b;
   }
   int RobberHouse(vector vec)
   {
   vector dp(vec.size(), 0);
   dp[0] = vec[0];
   dp[1] = maxT(vec[0], vec[1]);
   for (int i = 2; i < vec.size(); i++)
   {
   dp[i] = maxT(vec[i] + dp[i - 2], dp[i - 1]);
   }
   return dp.back();
   }
   int main()
   {
   vector vec{ -2,0,3,-5,2,-1 };
   RangeSumQueryImmutable R(vec);
   cout << R.sumRange(0, 2) << endl;
   cout << R.sumRange(2,5) << endl;
   cout << R.sumRange(0, 5) << endl;
   cout << RobberHouse({2,7,9,3,1}) << endl;
   system(“pause”);
   return 0;
   }