From 53793b70f9c9068bd45607d73465ed8256af30ac Mon Sep 17 00:00:00 2001
From: fw_qaq <82551626+Jack-Zhang-1314@users.noreply.github.com>
Date: Sat, 22 Oct 2022 21:55:08 +0800
Subject: [PATCH] update 18.4sum about rust

---
 problems/0018.四数之和.md | 36 +++++++++++++++++++----------------
 1 file changed, 20 insertions(+), 16 deletions(-)

diff --git a/problems/0018.四数之和.md b/problems/0018.四数之和.md
index 463eaf8f..ca33eb57 100644
--- a/problems/0018.四数之和.md
+++ b/problems/0018.四数之和.md
@@ -527,6 +527,7 @@ public class Solution
 
 Rust:
 ```Rust
+use std::cmp::Ordering;
 impl Solution {
     pub fn four_sum(nums: Vec<i32>, target: i32) -> Vec<Vec<i32>> {
         let mut result: Vec<Vec<i32>> = Vec::new();
@@ -545,22 +546,25 @@ impl Solution {
                 if i > k + 1 && nums[i] == nums[i - 1] { continue; }
                 let (mut left, mut right) = (i + 1, len - 1);
                 while left < right {
-                    if nums[k] + nums[i] > target - (nums[left] + nums[right]) {
-                        right -= 1;
-                        // 去重
-                        while left < right && nums[right] == nums[right + 1] { right -= 1; }
-                    } else if nums[k] + nums[i] < target - (nums[left] + nums[right]) {
-                        left += 1;
-                        // 去重
-                        while left < right && nums[left] == nums[left - 1] { left += 1; }
-                    } else {
-                        result.push(vec![nums[k], nums[i], nums[left], nums[right]]);
-                        // 去重
-                        while left < right && nums[right] == nums[right - 1] { right -= 1; }
-                        while left < right && nums[left] == nums[left + 1] { left += 1; }
-                        left += 1;
-                        right -= 1;
-                    }
+                    match (nums[k] + nums[i] + nums[left] + nums[right]).cmp(&target){
+		        Ordering::Equal => {
+			    result.push(vec![nums[k], nums[i], nums[left], nums[right]]);
+			    left += 1;
+			    right -= 1;
+			    while left < right && nums[left] == nums[left - 1]{
+			        left += 1;
+			    }
+			    while left < right && nums[right] == nums[right + 1]{
+			        right -= 1;
+			    }
+			}
+			Ordering::Less => {
+			    left +=1;
+			},
+			Ordering::Greater => {
+			    right -= 1;
+			}
+		    }
                 }
             }
         }