PHP Lottery algorithm

Original: http://blog.csdn.net/dongsg11200/article/details/24607877
PHP winning probability algorithm, can be used for scraping cards, large turntable and other lottery algorithm

4. <?php
6. /*
8. * Classical probability algorithm,
10. * $PROARR is a pre-set array,
12. * Suppose array is: Array (100,200,300,400),
14. * Start is to filter the first number from the probability range of 1,1000 within the range of his probability of occurrence,
16. * If not, then the probability space, that is, the value of K minus the probability space of the number just now,
18. * In this case, minus 100, which means the second number is filtered in the 1,900 range.
20. * This filter to the end, there will always be a number to meet the requirements.
22. * It's the equivalent of going to a box and touching something,
24. * The first is not, the second is not, the third one is not, and the last one must be.
26. * This algorithm is simple and highly efficient,
28. * The key is that this algorithm has been used in our previous projects, especially in large data volumes, which are very efficient.
30. */
32. function Get_rand ($proArr) {
34. $result = ";
36. The total probability accuracy of probability array
38. $proSum = array_sum ($proArr);
40. Probability array loop
42. foreach ($proArr as $key = = $proCur) {
44. $randNum = Mt_rand (1, $proSum);
46. if ($randNum <= $proCur) {
48. $result = $key;
50. Break
52. } Else {
54. $proSum-= $proCur;
56. }
58. }
60. unset ($PROARR);
62. return $result;
64. }
66. /*
68. * Awards Array
70. * is a two-dimensional array that records all the prize information for this draw,
72. * The ID indicates the winning level, prize represents the prize, and V indicates the probability of winning.
74. * Note that the V must be an integer, and you can set the V of the corresponding award to 0, which means that the odds of the prize being pumped are 0,
76. * The sum of V in the array (cardinality), the larger the cardinality, the more the probability of accuracy can be expressed.
78. * The sum of V in this example is 100, then the probability of winning the tablet corresponds to 1%,
80. * If the sum of V is 10000, then the probability of winning is one out of 10,000.
82. *
84. */
86. $prize _arr = Array (
88. ' 0 ' = = Array (' id ' =>1,' prize ' = 'tablet ',' V ' =>1),
90. ' 1 ' = = Array (' id ' =>2,' prize ' = 'digital camera ',' V ' =>5),
92. ' 2 ' = = Array (' id ' =>3,' prize ' = 'speaker device ',' V ' =>10),
94. ' 3 ' = = Array (' id ' =>4,' prize ' = ' 4G ', 'v ' =>12),
96. ' 4 ' = = Array (' id ' =>5,' prize ' = ' 10Q ', 'v ' =>22),
98. ' 5 ' = = Array (' id ' =>6,' prize ' = ' = 'next time it will be able to be in oh ',' V ' =>50),
100. );
102. /*
104. * Each front page request, PHP Loop Award set Array,
106. * Get the prize ID from the Get_rand by the probability calculation function.
108. * Save winning prizes in array $res[' yes ',
110. * While the remaining non-winning information is kept in $res[' no '),
112. * Finally output JSON data to the front page.
114. */
116. foreach ($prize _arr as $key = + $val) {
118. $arr [$val [' id ']] = $val [' V '];
120. }
122. $rid = Get_rand ($arr); //Get the prize ID based on probability
124. $res [' yes '] = $prize _arr[$rid -1][' Prize ']; //In the awards
126. unset ($prize _arr[$rid-1]); //The award is excluded from the array, leaving the award
128. Shuffle ($prize _arr); //scrambled array order
130. For ($i =0; $i <count ($prize _arr); $i + +) {
132. $PR [] = $prize _arr[$i] [' Prize '];
134. }
136. $res [' no '] = $pr;
138. Print_r ($res);
140. ?>

PHP Lottery algorithm