Added C++ solution

Anshul1507 · web-flow · commit 62db505df96c · 2020-10-03T21:51:22.000+05:30
31. Next Permutation C++ solution
diff --git a/cpp/_31.cpp b/cpp/_31.cpp
@@ -0,0 +1,33 @@
+class Solution {
+public:
+    void nextPermutation(vector<int>& nums) {
+    
+        int i1,i2;
+        bool hasPermutation = false;
+        for(int i=nums.size()-1;i>0;i--){
+            if(nums[i-1]<nums[i]){
+                i1 = i-1;
+                i2 = i;
+                hasPermutation = true;
+                break;
+            }
+        }
+        
+        if(hasPermutation){
+            int j=i2;
+            for(int i=nums.size()-1;i>i1;i--){
+                if(nums[i]>nums[i1]){
+                    j=i;
+                    break;
+                }
+            }
+            swap(nums[i1],nums[j]);
+            reverse(nums.begin()+i1+1,nums.end());
+        }else{
+            sort(nums.begin(),nums.end());
+        }
+        for(auto i:nums){
+            cout << i << " ";
+        }
+    }
+};
