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| class NumArray {
private final int[] prefixSumArray;
public NumArray(int[] nums) {
this.prefixSumArray = new int[nums.length + 1];
for (int i = 1; i < prefixSumArray.length; i++) {
prefixSumArray[i] = prefixSumArray[i - 1] + nums[i - 1];
}
}
public int sumRange(int left, int right) {
return prefixSumArray[right + 1] - prefixSumArray[left];
}
}
|
References
303. Range Sum Query - Immutable