算法讨论：从任意长度（N）的数组中取任意个（M）不重复的元素的所有组合
就是排列组合中的组合问题，比如用在双色球选号码上。
体育彩票那个是排列问题，大家有兴趣的也可以贡献代码。
var data = [0, 1, 2, 3, 4];
var out = [
[0, 1, 2],
[0, 1, 3],
[0, 1, 4],
[0, 2, 3],
[0, 2, 4],
[0, 3, 4],
[1, 2, 3],
[1, 2, 4],
[1, 3, 4],
[2, 3, 4]
];
6 回复
function gencombine(n, m) {
var combine = [];
if (m > n) return combine;
var stack = [];
var first = []
for (var i = 0; i < m; i++) {
stack[i] = i;
first[i] = i;
}
combine.push(first);
var last = [];
var end = n - m;
for (var i = 0; i < m; i++) {
last[i] = end + i;
}
var pos = m - 1;
var lastm = m - 1;
var temp;
while (true) {
if (stack[pos] < last[pos]) {
stack[pos]++;
temp = stack[pos];
pos++;
if (pos <= lastm) {
stack[pos] = temp;
}
} else {
pos--;
if (pos < 0) break;
}
if (pos > lastm) {
var tmp = [];
for (var i = 0; i < m; i++) {
tmp[i] = stack[i];
}
combine.push(tmp);
pos = lastm;
}
}
return combine;
}
var out = []; var data = [0, 1, 2, 3, 4]; var res = [];
function combi(arr, n, res){ if(n == 0){ out.push(res); return ; } if(arr.length == n){ out.push(res.concat(arr)); return ; }
for(var i=0;i<=arr.length-n;i++){ var temp = res.slice(0); temp.push(arr[i]); combi(arr.slice(i+1), n-1, temp); }
}
combi(data, 3, res); console.log(out);
