3

Author: kedebug

NextPermutation/NextPermutation.cpp

@@ -0,0 +1,34 @@
+class Solution {
+public:
+    void nextPermutation(vector<int>& num) {
+        // Start typing your C/C++ solution below
+        // DO NOT write int main() function
+        
+        int n = num.size();
+        if (n <= 1) return;
+        
+        bool found = false;
+        int i, p, maxval = INT_MIN;
+        for (i = n - 1; i >= 1; i--) {
+            if (maxval < num[i]) {
+                maxval = num[i];
+            }
+            if (num[i-1] < maxval) {
+                int delta = INT_MAX;
+                for (int j = i; j < n; j++) {
+                    if (num[j] > num[i-1] && num[j] - num[i-1] < delta)
+                        p = j;
+                }
+                found = true; 
+                break;
+            }
+        }
+        if (!found) {
+            reverse(num.begin(), num.end());
+        }
+        else {
+            swap(num[p], num[i-1]);
+            sort(num.begin() + i, num.end());
+        }
+    }
+};