Update README.md

Author: yanglbme

lcof2/剑指 Offer II 104. 排列的数目/README.md

@@ -147,16 +147,16 @@ func combinationSum4(nums []int, target int) int {
 class Solution {
     func combinationSum4(_ nums: [Int], _ target: Int) -> Int {
         var dp = [Int](repeating: 0, count: target + 1)
-        dp[0] = 1 
+        dp[0] = 1
 
         for i in 1...target {
             for num in nums {
-                if i >= num {
+                if i >= num, dp[i] <= Int.max - dp[i - num] {
                     dp[i] += dp[i - num]
                 }
             }
         }
-        
+
         return dp[target]
     }
 }