# PHP probabilistic algorithm (RPM)

Source: Internet
Author: User

`Cases:function Get_rand (\$PROARR) {     \$result = ';     The total probability accuracy of the probability array    \$proSum = Array_sum (\$PROARR);     Probability array Loop    foreach (\$proArr as \$key + = \$proCur) {         \$randNum = Mt_rand (1, \$proSum);         if (\$randNum <= \$proCur) {             \$result = \$key;             break;         } else {             \$proSum-= \$proCur;         }     }     Unset (\$PROARR);     return \$result; }`

\$prize _arr is a two-dimensional array that records all of the prize information for this draw, where the ID indicates the winning grade, prize represents the prize, and V indicates the probability of winning. Note that the V must be an integer, and you can set the V of the corresponding prize to 0, meaning that the odds of the prize being pumped are 0, the sum of V in the array (cardinality), and the larger the cardinality, the more accurate the probability. In this case, the sum of V is 100, then the winning probability of the tablet computer is 1%, if the sum of V is 10000, then the probability of winning is one out of 10,000.

`\$prize _arr = Array (' 0 ' = = Array ('     id ' =>1, ' prize ' = ' computer ', ' V ' =>1),     ' 1 ' = = Array (' ID ' =>2, ' Prize ' + ' camera ', ' V ' =>5),     ' 2 ' = = Array (' ID ' =>3, ' prize ' = ' Speaker ', ' V ' =>10),     ' 3 ' = = Array (' id ' = >4, ' prize ' = ' USB ', ' V ' =>12, '     4 ' = = Array (' ID ' =>5, ' prize ' = ' Q ', ' V ' =>22),     ' 5 ' = Array (' ID ' =>6, ' prize ' = ' refueling ', ' V ' =>50),);  `

Every time a front-end page is requested, the PHP loop prizes are set in an array, using the probability calculation function Get_rand to get the prize ID in the drawing. Save the winning prize in the array \$res[' yes ', and the remaining non-winning information is saved in \$res[' no ', and finally output JSON data to the front page.

`If the winning data is placed in the database, it is necessary to determine the number of winning//in the 1, 2, 3 and other prizes, if the maximum number of unset corresponding awards, avoid repeating the jackpot//code here Eg:unset (\$prize _arr[' 0 ') foreach (\$prize _arr as \$key + \$val) {     \$arr [\$val [' id ']] = \$val [' V '];} \$rid = Get_rand (\$arr);//probability of obtaining the prize id\$res[' Yes '] = \$prize _arr[\$rid -1][' Prize '); In the awards//will be excluded from the array, the remaining awards, if the database validation, here can be omitted unset (\$prize _arr[\$rid-1]); Shuffle (\$prize _arr); Scrambled array order for (\$i =0; \$i <count (\$prize _arr); \$i + +) {     \$PR [] = \$prize _arr[\$i] [' Prize '];} \$res [' no '] = \$PR; Echo json_ Encode (\$res);   `

PHP probabilistic algorithm (RPM)

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