# 303. Range Sum Query - Immutable

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:

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

``````class NumArray {
public:
NumArray(vector<int> &nums) {
dp = nums;
for (int i = 1; i < nums.size(); ++i) {
dp[i] += dp[i - 1];
}
}
int sumRange(int i, int j) {
return i == 0? dp[j] : dp[j] - dp[i - 1];
}
private:
vector<int> dp;
};
``````

``````class NumArray {
public:
NumArray(vector<int> &nums) {
dp.resize(nums.size() + 1, 0);
for (int i = 1; i <= nums.size(); ++i) {
dp[i] = dp[i - 1] + nums[i - 1];
}
}
int sumRange(int i, int j) {
return dp[j + 1] - dp[i];
}

private:
vector<int> dp;
};
``````

Range Sum Query 2D - Mutable

Range Sum Query 2D - Immutable

Range Sum Query - Mutable

https://leetcode.com/problems/range-sum-query-immutable/

https://leetcode.com/problems/range-sum-query-immutable/discuss/75184/5-lines-C%2B%2B-4-lines-Python

https://leetcode.com/problems/range-sum-query-immutable/discuss/75192/Java-simple-O(n)-init-and-O(1)-query-solution

LeetCode All in One 题目讲解汇总(持续更新中…)

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