Range Sum Query Immutable Problem & Solution
Given an integer array nums, handle multiple queries of the following type:
Calculate the sum of the elements of nums between indices left and right inclusive where left <= right.
Implement the NumArray class:
NumArray(int[] nums)Initializes the object with the integer array nums.int sumRange(int left, int right)Returns the sum of the elements ofnumsbetween indicesleftandrightinclusive (i.e.nums[left] + nums[left + 1] + ... + nums[right]).
See the range sum query immutable problem on LeetCode.
C++ Solution
#pragma GCC optimize("Ofast")
#pragma GCC optimization("unroll-loops")
static const int _=[](){ios::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);return 0;}();
/**
* Your NumArray object will be instantiated and called as such:
* NumArray* obj = new NumArray(nums);
* int param_1 = obj->sumRange(left,right);
*/
class NumArray {
public:
NumArray(vector<int>& nums) {
sums = vector<int>(nums.size() + 1, 0);
for (int i = 0; i < nums.size(); ++i) {
sums[i + 1] = sums[i] + nums[i];
}
}
int sumRange(int left, int right) {
return sums[right + 1] - sums[left];
}
private:
vector<int> sums;
};