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37 lines
1.2 KiB
Rust
37 lines
1.2 KiB
Rust
1 year ago
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use std::cmp::Ordering;
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fn trap(height: Vec<i32>) -> i32 {
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// base case
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if height.len() == 0 {
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return 0;
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}
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let (mut l, mut r) = (0, height.len() - 1); // left and right pointer
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let (mut l_max, mut r_max) = (height[l], height[r]); // left and right max height of current pointer
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let mut res = 0;
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while l < r { // loop until left and right pointer meet
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match l_max.cmp(&r_max) { // compare left and right max height
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Ordering::Less => { // if left max height is less than right max height means we can trap water in left side
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l += 1; // move left pointer
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l_max = std::cmp::max(l_max, height[l]); // update left max height
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res += l_max - height[l]; // add water
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},
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_ => { // if right max height is less than left max height means we can trap water in right side
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r -= 1; // move right pointer
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r_max = std::cmp::max(r_max, height[r]); // update right max height
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res += r_max - height[r]; // add water
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}
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}
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}
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res
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}
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fn main() {
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let height = vec![0,1,0,2,1,0,1,3,2,1,2,1];
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let res = trap(height);
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println!("res = {}", res);
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}
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