From d75905bfbe517721442b867eaac6e4181f36bfef Mon Sep 17 00:00:00 2001
From: ShusenTang <tangshusen@pku.edu.cn>
Date: Sat, 4 Jul 2020 20:04:42 +0800
Subject: [PATCH] update code2

---
 solutions/204. Count Primes.md | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/solutions/204. Count Primes.md b/solutions/204. Count Primes.md
index 3e414d4..470c96f 100644
--- a/solutions/204. Count Primes.md	
+++ b/solutions/204. Count Primes.md	
@@ -37,14 +37,15 @@ public:
 class Solution {
 public:
     int countPrimes(int n) {
-        vector<unsigned int>nums(n, 1); // 0代表被划去，1代表没被划去 
-        int count = 0;
+        vector<bool>Prime(n + 1, true);
+        int res = 0;
         for(int i = 2; i < n; i++){
-            if(nums[i] == 0) continue;
-            count++;
-            for(int j = 2; j * i < n; j++) nums[j * i] = 0;
+            if(Prime[i]){
+                res++;
+                for(int j = i; j <= n / i; j++) Prime[i*j] = false;
+            }
         }
-        return count;
+        return res;
     }
 };
 ```