58 lines
1.2 KiB
Rust
58 lines
1.2 KiB
Rust
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/**
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* [303] Range Sum Query - Immutable
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*/
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pub struct Solution {}
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// submission codes start here
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struct NumArray {
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prefix_array: Vec<i32>,
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}
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/**
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* `&self` means the method takes an immutable reference.
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* If you need a mutable reference, change it to `&mut self` instead.
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*/
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impl NumArray {
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fn new(nums: Vec<i32>) -> Self {
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let mut prefix_array = Vec::with_capacity(nums.len());
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for (index, value) in nums.iter().enumerate() {
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if index == 0 {
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prefix_array.push(*value);
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} else {
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prefix_array.push(prefix_array[index - 1] + *value);
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}
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}
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NumArray { prefix_array }
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}
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fn sum_range(&self, left: i32, right: i32) -> i32 {
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let left = left as usize;
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let right = right as usize;
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return if left == 0 {
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self.prefix_array[right]
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} else {
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self.prefix_array[right] - self.prefix_array[left - 1]
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};
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}
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}
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/**
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* Your NumArray object will be instantiated and called as such:
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* let obj = NumArray::new(nums);
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* let ret_1: i32 = obj.sum_range(left, right);
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*/
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// submission codes end
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn test_303() {}
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}
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