Update 031._next_permutation.md

031._next_permutation.md

@@ -92,7 +92,7 @@ class Solution(object):
                 idx = i
                 break
         if idx != 0: # if the number exist,which means that the nums not like{5,4,3,2,1}
-            for i in range(len(nums)-1, 0, -1):
+            for i in range(len(nums)-1, idx-1, -1):
                 if nums[i] > nums[idx-1]:
                     nums[i], nums[idx-1] = nums[idx-1], nums[i]
                     break