Leetcode 303. Range Sum Query - Immutable (Easy) (cpp)

Leetcode 303. Range Sum Query - Immutable (Easy) (cpp)

Tag: Dynamic Programming

Difficulty: Easy

/*

303. Range Sum Query - Immutable (Easy)

Given an integer array nums, find the sum of the elements between indices i and j (i ≤ j), inclusive.

Example:
Given nums = [-2, 0, 3, -5, 2, -1]

sumRange(0, 2) -> 1
sumRange(2, 5) -> -1
sumRange(0, 5) -> -3

Note:
You may assume that the array does not change.
There are many calls to sumRange function.

*/
class NumArray {
public:
vector<int> table;
NumArray(vector<int> &nums) {
int sum = 0;
for (int i : nums) {
sum += i;
table.push_back(sum);
}
}

int sumRange(int i, int j) {
if (!i) return table[j];
return table[j] - table[i - 1];
}
};

// Your NumArray object will be instantiated and called as such:
// NumArray numArray(nums);
// numArray.sumRange(0, 1);
// numArray.sumRange(1, 2);