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Copy pathNumArray1.java
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24 lines (18 loc) · 857 Bytes
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/* 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 of nums between indices left and right inclusive (i.e. nums[left] + nums[left + 1] + ... + nums[right]). */
class NumArray {
private int[] prefixSums;
public NumArray(int[] nums) {
int n = nums.length;
prefixSums = new int[n + 1]; // prefixSums[0] = 0
for (int i = 0; i < n; i++) {
prefixSums[i + 1] = prefixSums[i] + nums[i];
}
}
public int sumRange(int left, int right) {
return prefixSums[right + 1] - prefixSums[left];
}
}