solve 16

Author: StephenLeeUSTC

src/solution/mod.rs

@@ -42,3 +42,4 @@ mod s0455_assign_cookies;
 mod s0986_interval_list_intersections;
 mod s0855_exam_room;
 mod s0881_boats_to_save_people;
+mod s0016_3sum_closest;

src/solution/s0016_3sum_closest.rs

@@ -0,0 +1,105 @@
+/**
+ * [16] 3Sum Closest
+ *
+ * Given an integer array nums of length n and an integer target, find three integers in nums such that the sum is closest to target.
+ * Return the sum of the three integers.
+ * You may assume that each input would have exactly one solution.
+ *  
+ * Example 1:
+ * 
+ * Input: nums = [-1,2,1,-4], target = 1
+ * Output: 2
+ * Explanation: The sum that is closest to the target is 2. (-1 + 2 + 1 = 2).
+ * 
+ * Example 2:
+ * 
+ * Input: nums = [0,0,0], target = 1
+ * Output: 0
+ * 
+ *  
+ * Constraints:
+ * 
+ * 	3 <= nums.length <= 1000
+ * 	-1000 <= nums[i] <= 1000
+ * 	-10^4 <= target <= 10^4
+ * 
+ */
+pub struct Solution {}
+
+// problem: https://leetcode.com/problems/3sum-closest/
+// discuss: https://leetcode.com/problems/3sum-closest/discuss/?currentPage=1&orderBy=most_votes&query=
+
+// submission codes start here
+
+impl Solution {
+    pub fn three_sum_closest(nums: Vec<i32>, target: i32) -> i32 {
+        let mut inputs = nums.clone();
+        inputs.sort();
+        // println!("inputs is {:?}", inputs);
+        let mut res = 0;
+        let mut diff = std::i32::MAX;
+
+        for i in 0..inputs.len() {
+            let mut j = i + 1;
+            let mut k = inputs.len() - 1;
+            let mut sum = 0;
+            while j < k {
+                sum = inputs[i] + inputs[j] + inputs[k];
+                // println!("i, j , k is {}, {}, {}, sum is {}", i, j, k, sum);
+                if sum == target {
+                    return sum;
+                } else if sum < target {
+                    if i32::abs(sum - target) < diff {
+                        diff = i32::abs(sum - target);
+                        res = sum;
+                    }
+                    j += 1;
+                } else {
+                    if i32::abs(sum - target) < diff {
+                        diff = i32::abs(sum - target);
+                        res = sum;
+                    }
+                    k -= 1;
+                }
+            }
+
+        }
+
+        res
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_16_0() {
+        let nums = vec![-1,2,1,-4];
+        let target = 1;
+        assert_eq!(Solution::three_sum_closest(nums, target), 2);
+    }
+
+    #[test]
+    fn test_16_1() {
+        let nums = vec![0, 0, 0];
+        let target = 1;
+        assert_eq!(Solution::three_sum_closest(nums, target), 0);
+    }
+
+    #[test]
+    fn test_16_3() {
+        let nums = vec![0, 1, 2];
+        let target = 3;
+        assert_eq!(Solution::three_sum_closest(nums, target), 3);
+    }
+
+    #[test]
+    fn test_16_4() {
+        let nums = vec![1, 1, 1, 0];
+        let target = -100;
+        assert_eq!(Solution::three_sum_closest(nums, target), 2);
+    }
+}