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    "# permute\n",
    "Tutorial illustrating the use of TMath::Permute for computing all permutations of n natural numbers.\n",
    "\n",
    "It can be run with:\n",
    "\n",
    "```cpp\n",
    "root > .x permute.C\n",
    "root > .x permute.C+ with ACLIC\n",
    "```\n",
    "\n",
    "\n",
    "\n",
    "\n",
    "**Author:** Federico Carminati  \n",
    "<i><small>This notebook tutorial was automatically generated with <a href= \"https://github.com/root-project/root/blob/master/documentation/doxygen/converttonotebook.py\">ROOTBOOK-izer</a> from the macro found in the ROOT repository  on Tuesday, May 19, 2026 at 08:27 PM.</small></i>"
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    " Definition of a helper function: "
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    "%%cpp -d\n",
    "\n",
    "#include <TMath.h>\n",
    "\n",
    "int permuteSimple1 ()\n",
    "{\n",
    "  printf(\"\\nTMath::Permute simple test\\n\");\n",
    "  printf(\"==========================\\n\");\n",
    "  char aa='a';\n",
    "  Int_t a[4];\n",
    "  Int_t i;\n",
    "  Int_t icount=0;\n",
    "  for(i=0; i<4; i++) a[i]=i;\n",
    "  do {\n",
    "    icount++;\n",
    "    for(Int_t i=0;i<4;printf(\"%c\",static_cast<char>(aa+a[i++])));\n",
    "    printf(\"\\n\");\n",
    "\n",
    "  } while(TMath::Permute(4,a));\n",
    "  printf(\"Found %d permutations = 4!\\n\",icount);\n",
    "  return 0;\n",
    "}"
   ]
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   "source": [
    "%%cpp -d\n",
    "int permuteSimple2 ()\n",
    "{\n",
    "  printf(\"\\nTMath::Permute simple test with repetition\\n\");\n",
    "  printf(\"==========================================\\n\");\n",
    "  char aa='a'-1;\n",
    "  Int_t a[6];\n",
    "  Int_t i;\n",
    "  Int_t icount=0;\n",
    "  for(i=0; i<6; i++) a[i]=(i+2)/2;\n",
    "  do {\n",
    "     icount++;\n",
    "     for(Int_t i=0;i<5;printf(\"%c\",static_cast<char>(aa+a[i++])));\n",
    "     printf(\"\\n\");\n",
    "\n",
    "  } while(TMath::Permute(5,a));\n",
    "  printf(\"Found %d permutations = 5!/(2! 2!)\\n\",icount);\n",
    "  return 0;\n",
    "}"
   ]
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   "source": [
    "%%cpp -d\n",
    "Int_t permuteFancy()\n",
    "{\n",
    "  Int_t a[10];\n",
    "  Int_t &n=a[0], &i=a[1];\n",
    "  Int_t &e=a[2], &t=a[3];\n",
    "  Int_t &h=a[4], &r=a[5];\n",
    "  Int_t &f=a[6], &o=a[7];\n",
    "  Int_t &s=a[8], &u=a[9];\n",
    "  Int_t nine, three, neuf, trois;\n",
    "\n",
    "  printf(\"\\nTMath::Permute fancy test\\n\");\n",
    "  printf(\"=========================\\n\");\n",
    "  printf(\"This is a program to calculate the solution to the following problem\\n\");\n",
    "  printf(\"Find the equivalence between letters and numbers so that\\n\\n\");\n",
    "  printf(\"              NINE*THREE = NEUF*TROIS\\n\\n\");\n",
    "  for(Int_t ii=0; ii<10; ii++) a[ii]=ii;\n",
    "  do {\n",
    "     nine=((n*10+i)*10+n)*10+e;\n",
    "     neuf=((n*10+e)*10+u)*10+f;\n",
    "     three=(((t*10+h)*10+r)*10+e)*10+e;\n",
    "     trois=(((t*10+r)*10+o)*10+i)*10+s;\n",
    "     if(nine*three==neuf*trois) {\n",
    "        printf(\"Solution found!\\n\\n\");\n",
    "        printf(\"T=%d N=%d E=%d S=%d F=%d H=%d R=%d I=%d O=%d U=%d\\n\",t,n,e,s,f,h,r,i,o,u);\n",
    "        printf(\"NINE=%d THREE=%d NEUF=%d TROIS=%d\\n\",nine,three,neuf,trois);\n",
    "        printf(\"NINE*THREE = NEUF*TROIS = %d\\n\",neuf*trois);\n",
    "        return 0;\n",
    "     }\n",
    "  } while(TMath::Permute(10,a));\n",
    "  printf(\"No solutions found -- something is wrong here!\\n\");\n",
    "  return 0;\n",
    "}"
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     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\n",
      "TMath::Permute simple test\n",
      "==========================\n",
      "abcd\n",
      "abdc\n",
      "acbd\n",
      "acdb\n",
      "adbc\n",
      "adcb\n",
      "bacd\n",
      "badc\n",
      "bcad\n",
      "bcda\n",
      "bdac\n",
      "bdca\n",
      "cabd\n",
      "cadb\n",
      "cbad\n",
      "cbda\n",
      "cdab\n",
      "cdba\n",
      "dabc\n",
      "dacb\n",
      "dbac\n",
      "dbca\n",
      "dcab\n",
      "dcba\n",
      "Found 24 permutations = 4!\n",
      "\n",
      "TMath::Permute simple test with repetition\n",
      "==========================================\n",
      "aabbc\n",
      "aabcb\n",
      "aacbb\n",
      "ababc\n",
      "abacb\n",
      "abbac\n",
      "abbca\n",
      "abcab\n",
      "abcba\n",
      "acabb\n",
      "acbab\n",
      "acbba\n",
      "baabc\n",
      "baacb\n",
      "babac\n",
      "babca\n",
      "bacab\n",
      "bacba\n",
      "bbaac\n",
      "bbaca\n",
      "bbcaa\n",
      "bcaab\n",
      "bcaba\n",
      "bcbaa\n",
      "caabb\n",
      "cabab\n",
      "cabba\n",
      "cbaab\n",
      "cbaba\n",
      "cbbaa\n",
      "Found 30 permutations = 5!/(2! 2!)\n",
      "\n",
      "TMath::Permute fancy test\n",
      "=========================\n",
      "This is a program to calculate the solution to the following problem\n",
      "Find the equivalence between letters and numbers so that\n",
      "\n",
      "              NINE*THREE = NEUF*TROIS\n",
      "\n",
      "Solution found!\n",
      "\n",
      "T=1 N=9 E=6 S=7 F=8 H=3 R=2 I=0 O=5 U=4\n",
      "NINE=9096 THREE=13266 NEUF=9648 TROIS=12507\n",
      "NINE*THREE = NEUF*TROIS = 120667536\n"
     ]
    }
   ],
   "source": [
    "permuteSimple1();\n",
    "permuteSimple2();\n",
    "permuteFancy();"
   ]
  }
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