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0015-3sum/Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "leetcode"
+version = "0.1.0"

0015-3sum/Cargo.toml

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+[package]
+name = "leetcode"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]

0015-3sum/src/main.rs

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+fn main() {
+    println!("Hello, world!");
+}
+
+pub fn three_sum(nums: Vec<i32>) -> Vec<Vec<i32>> {
+    let mut result = vec![];
+
+    if nums.len() < 3 {
+        return result;
+    }
+
+    let mut nums: Vec<_> = nums;
+    nums.sort_unstable();
+
+    for idx in 0..nums.len() - 1 {
+        let first = nums[idx];
+
+        if first > 0 {
+            // no more negative numbers left, so we are done
+            break;
+        }
+
+        if idx > 0 && first == nums[idx - 1] {
+            // we already scanned for this number
+            continue;
+        }
+        let mut left = idx + 1;
+        let mut right = nums.len() - 1;
+
+        while left < right {
+            let sum = first + nums[left] + nums[right];
+            if sum == 0 {
+                let entry = vec![first, nums[left], nums[right]];
+                result.push(entry);
+
+                // skip identical numbers that would lead to the same combinations
+                while nums[left + 1] == nums[left] && left < nums.len() - 2 {
+                    left += 1;
+                }
+
+                while nums[right - 1] == nums[right] && right > 1 {
+                    right -= 1;
+                }
+            }
+            if sum <= 0 {
+                left += 1;
+            } else {
+                right -= 1;
+            }
+        }
+    }
+
+    result
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::three_sum;
+
+    #[test]
+    fn test_1() {
+        let sums = three_sum(vec![-1, 0, 1, 2, -1, -4]);
+
+        assert_eq!(sums.len(), 2);
+        assert!(sums.contains(&vec![-1, -1, 2]));
+        assert!(sums.contains(&vec![-1, 0, 1]));
+    }
+
+    #[test]
+    fn test_2() {
+        let sums = three_sum(vec![0, 1, 1]);
+        assert_eq!(sums, Vec::<Vec<i32>>::new());
+    }
+
+    #[test]
+    fn test_3() {
+        let sums = three_sum(vec![0, 0, 0]);
+        assert_eq!(sums, vec![vec![0, 0, 0]]);
+    }
+
+    #[test]
+    fn test_4() {
+        let sums = three_sum(vec![
+            2, -3, 0, -2, -5, -5, -4, 1, 2, -2, 2, 0, 2, -4, 5, 5, -10,
+        ]);
+        assert_eq!(sums.len(), 6);
+    }
+}