diff --git a/include/s0031_next_permutation.hpp b/include/s0031_next_permutation.hpp
new file mode 100644
index 0000000..a3c4fd3
--- /dev/null
+++ b/include/s0031_next_permutation.hpp
@@ -0,0 +1,13 @@
+#ifndef S0031_NEXT_PERMUTATION
+#define S0031_NEXT_PERMUTATION
+
+#include <vector>
+
+using namespace std;
+
+class Solution {
+ public:
+  void nextPermutation(vector<int>& nums);
+};
+
+#endif
diff --git a/src/s0031_next_permutation.cpp b/src/s0031_next_permutation.cpp
new file mode 100644
index 0000000..76173b6
--- /dev/null
+++ b/src/s0031_next_permutation.cpp
@@ -0,0 +1,16 @@
+#include "s0031_next_permutation.hpp"
+
+void Solution::nextPermutation(vector<int>& nums) {
+  int i = nums.size() - 2;
+  while (i >= 0 && nums[i] >= nums[i + 1]) {
+    i--;
+  }
+  if (i >= 0) {
+    int j = nums.size() - 1;
+    while (j >= 0 && nums[i] >= nums[j]) {
+      j--;
+    }
+    swap(nums[i], nums[j]);
+  }
+  reverse(nums.begin() + i + 1, nums.end());
+}