feat: add next_permutations_with_reps snippets

Author: LuchoBazz

brute_force/brute_force_next_permutation_with_reps.cpp

@@ -0,0 +1,58 @@
+// N = len of v
+// O(N^(r - l + 1) * N)
+bool next_permutations_with_reps(vector<int> &v, int l, int r) {
+    assert(l < r && !v.empty());
+    if (all_of(v.begin(), v.end(), [&](int x) { return x == r; }))
+        return false;
+
+    for (int i = int(v.size()) - 1; i >= 0; --i) {
+        if (v[i] == r) {
+            v[i] = l;
+        } else {
+            ++v[i];
+            return true;
+        }
+    }
+    return false;
+}
+// Usage:
+// int n = 3, l = 1, r = 3, cnt = 1;
+// vector<int> v(n, l);
+// do {
+//     cout << cnt++ << ") ";
+//     for (auto &x : v) {
+//         cout << x << ' ';
+//     }
+//     cout << '\n';
+// } while (next_permutations_with_reps(v, l, r));
+
+// Sample:
+// n=3, l=1, r=3
+// {1, 2, 3} * {1, 2, 3} * {1, 2, 3} = 3 * 3 * 3 = 27
+// 1) 1 1 1 
+// 2) 1 1 2 
+// 3) 1 1 3 
+// 4) 1 2 1 
+// 5) 1 2 2 
+// 6) 1 2 3 
+// 7) 1 3 1 
+// 8) 1 3 2 
+// 9) 1 3 3 
+// 10) 2 1 1 
+// 11) 2 1 2 
+// 12) 2 1 3 
+// 13) 2 2 1 
+// 14) 2 2 2 
+// 15) 2 2 3 
+// 16) 2 3 1 
+// 17) 2 3 2 
+// 18) 2 3 3 
+// 19) 3 1 1 
+// 20) 3 1 2 
+// 21) 3 1 3 
+// 22) 3 2 1 
+// 23) 3 2 2 
+// 24) 3 2 3 
+// 25) 3 3 1 
+// 26) 3 3 2 
+// 27) 3 3 3