├── cyclic_algo.js
├── even.png
├── odd.png
└── readme.md


/cyclic_algo.js:
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  1 | 
  2 | function pairingsTeams(numOfTeams, numOfRounds) {
  3 | 
  4 |     var pairs = [];
  5 |     var teamHAObj = {};
  6 |     var teamGObj = {};
  7 |     var roundObj = {};
  8 | 
  9 |     var isOddTeam = numOfTeams % 2 == 0 ? false : true;
 10 |     var bye = -1;
 11 |     var home, away;
 12 |     var generatePairs = function(){
 13 |         var pairNum = Math.floor( (numOfTeams - 1) / 2);
 14 |         
 15 |         // Initialize the list of teams
 16 |         var teams = Array(numOfTeams).fill().map((val,idx) => idx + 1);
 17 |         // if (isOddTeam) teams.push(bye);
 18 |         if (isOddTeam) teams.unshift(bye);
 19 | 
 20 |         for (var r = 1; r < numOfRounds+1; r++) {
 21 |             var rndN = `round ${r}`;
 22 |             roundObj[rndN] = [];
 23 |             for (var k = 0; k < pairNum; k++) {
 24 |                 if ((pairNum - k) % 2 != 0) {
 25 |                     home = teams[pairNum - k];
 26 |                     away = teams[pairNum + k + 1];
 27 |                 } else {
 28 |                     home = teams[pairNum + k + 1];
 29 |                     away = teams[pairNum - k];
 30 |                 }
 31 |                 
 32 |                 pairs.push(`${home},${away}`);
 33 |                 roundObj[rndN].push(`${home},${away}`);
 34 |             }
 35 | 
 36 |             if (!isOddTeam) {
 37 |                 if (r % 2 == 0){
 38 |                     home = teams[0];
 39 |                     away = teams[teams.length - 1];
 40 |                 } else {
 41 |                     home = teams[teams.length - 1];
 42 |                     away = teams[0];
 43 |                 }
 44 | 
 45 |                 pairs.push(`${home},${away}`);
 46 |                 roundObj[rndN].push(`${home},${away}`);
 47 |             }
 48 |                 
 49 | 
 50 |             // rotate team array
 51 |             var last = teams.pop();
 52 |             teams.splice(1, 0, last);
 53 |         }
 54 |     }
 55 | 
 56 |     var spliteHomeAway = function(){
 57 |         pairs.forEach(function(i) {
 58 |             var key = i;
 59 |             let away = key.split(',')[1];
 60 |             let home = key.split(',')[0];
 61 | 
 62 |             if (!teamHAObj[away]) {
 63 |                 teamHAObj[away] = {home:0, away: 0};
 64 |             }
 65 |             if (!teamHAObj[home]) {
 66 |                 teamHAObj[home] =  {home:0, away: 0};
 67 |             }
 68 | 
 69 |             teamHAObj[away]['away'] += 1;
 70 |             teamHAObj[home]['home'] += 1;
 71 |         })
 72 |     }
 73 | 
 74 |     var gamesPerTeam = function(){
 75 |         pairs.forEach(function(i) {
 76 |             var key = i;
 77 |             let away = key.split(',')[1];
 78 |             let home = key.split(',')[0];
 79 | 
 80 |             if (!teamGObj[away]) {
 81 |                 teamGObj[away] = {[home]: 0}
 82 |             }
 83 | 
 84 |             if (!teamGObj[home]) {
 85 |                 teamGObj[home] = {[away]: 0}
 86 |             }
 87 | 
 88 |             if (!teamGObj[away][home]) {
 89 |                 teamGObj[away][home] = 0
 90 |             }
 91 | 
 92 |             if (!teamGObj[home][away]) {
 93 |                 teamGObj[home][away] = 0
 94 |             }
 95 | 
 96 |             teamGObj[away][home] += 1;
 97 |             teamGObj[home][away] += 1;
 98 |         })
 99 |     }
100 | 
101 |     generatePairs();
102 |     spliteHomeAway();
103 |     gamesPerTeam();
104 | 
105 |     console.log(">>>>>>>>>>>>>>>>>>>>>>>");
106 |     console.log(`teams: ${numOfTeams}, rounds: ${numOfRounds}`);
107 |     console.log("Pairs >>>>>>>>>>>>>>>>>");
108 |     console.log(pairs);
109 |     console.log("Rounds Breakdown >>>>>>");
110 |     console.log(roundObj);
111 |     console.log("Home/Away Breakdown >>>");
112 |     console.log(teamHAObj);
113 |     console.log("number of games with other teams per team >>>");
114 |     console.log(JSON.stringify(teamGObj, null, 2));
115 | }
116 | 
117 | // pairingsTeams(11,9);
118 | // pairingsTeams(4,11);
119 | // pairingsTeams(8,4);
120 | pairingsTeams(5,10);


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/even.png:
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https://raw.githubusercontent.com/jsguru-git/round_robin_scheduler/76392f3e771c3f5f8da35883a5d4af6b5c3edfcf/even.png


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/odd.png:
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https://raw.githubusercontent.com/jsguru-git/round_robin_scheduler/76392f3e771c3f5f8da35883a5d4af6b5c3edfcf/odd.png


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/readme.md:
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 1 | # Round robin tournament generator
 2 | 
 3 | ## Round robin for **even** number of teams
 4 | ![round robin for even number of teams](even.png)
 5 | ```
 6 | {
 7 |   'round 1': [ '4,3', '2,5', '6,1' ],
 8 |   'round 2': [ '3,2', '6,4', '1,5' ],
 9 |   ...
10 | }
11 | ```
12 | 
13 | ## Round robin for **odd** number of teams
14 | ![round robin for odd number of teams](odd.png)
15 | ```
16 | {
17 |   'round 1': [ '3,4', '5,2', '1,6' ],
18 |   'round 2': [ '2,3', '4,1', '7,5' ],
19 |   ...
20 | }
21 | ```


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