js实现指定红包顺序和金额算法
本文实例为大家分享了js实现指定红包顺序和金额的具体代码,供大家参考,具体内容如下
前言
- 朋友拜托而写
- 单个包最小金额为0.01
- 如果除指定金额外,其余都为0.01,最后尾包存在为0的几率
- 本算法通过了1000000次测试,出错率为百万分之3
效果展示
空包问题
红包算法
/* param: float, int, int, float param1:红包金额总额 param2:红包数目 param3:指定特殊红包 param4:指定特殊红包金额 */ let getPrize = function(total, number, index, volume){ let allowance = total - volume; let arr = []; let i = 0; while(i < number - 2){ // 指定[0.01,allowance-(i*0.01)) let temp = (Math.random()*(allowance - (number - 1 - i) * 0.01) + 0.01).toFixed(2); // if(temp < 0) console.log(`temp:${temp}`); temp = temp <= 0 ? 0.01 : temp; arr.push(parseFloat(temp)); allowance = parseFloat((allowance - temp).toFixed(2)); i++; // console.log(`arr:${arr}, i:${i}`); // 如果出现小于0的分配情况,剥削强者均分 if(allowance <= 0){ // console.log(`alowance:${allowance}`); let w = arr.filter((val,index)=>{ // console.log(`val:${val}`); if(val > 0.01){ arr[index] = parseFloat((arr[index] - 0.01).toFixed(2)); return val; } }); if(w.length == 0){ allowance = 0; }else{ allowance = 0.01; } } } // 最后一个放入 arr.push(parseFloat(allowance.toFixed(2))); let result = arr; return result.slice(0, index).concat(parseFloat(volume), result.slice(index)); }
测试样例
// Test sample for(let m = 0; m < 10000; m++){ let total = (Math.random()*100 + 0.01).toFixed(2); let number = Math.floor(Math.random()*20 +2); while(total / number < 0.01){ number = Math.floor(Math.random()*20 +2); } let index = Math.floor(Math.random()*(number - 1)); let volume = (Math.random()*(total - 0.01*(number-1))+0.01).toFixed(2); while(volume >= total || volume + 0.01*(number-1) > total){ // console.log(`xx:${volume}`); volume = (Math.random()*(total - 0.01*(number-1))+0.01).toFixed(2); volume = volume <= 0 ? 0.01 : volume; } let test = getPrize(total, number, index, volume); // console.log(test); let sum = test.reduce((total,val)=>total+=parseFloat(val)); sum = sum.toFixed(2); if(sum !== total) { console.log(`volume:${volume}, total: ${total}, number: ${number}`); console.log(`sum:${sum}`); console.log(test); } test.map((val,index)=>{ if(val <= 0 && index !== test.length - 1){ console.log(`volume:${volume}, total: ${total}, number: ${number}`); console.log(`sum:${sum}`); console.log(test); } }); }
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