假设数组为：[1，2，5，7，10，13，17，21]，你必须找到5个号码的总和等于31。什么是算法

Suppose array is: [1, 2, 5, 7, 10, 13, 17, 21] and you have to find 5 numbers whose sum is equal to 31. What would be the algorithm?

推荐答案

有关一小阵如您有，效率没有多大的意义。关键是要让它快。像这样的工作（MATLAB写的，但它会很容易翻译成任何语言）：

For a small array such as you have, efficiency doesn't mean much. The trick is to make it fast. Something like this would work (Written in Matlab, but it would translate to any language fairly easily):

array=[1, 2, 5, 7, 10, 13, 17, 21];
sum_val=31;

for a=1:(length(array)-4]
for b=(a+1):(length(array)-3)
for c=(b+1):(length(array)-2)
for d=(c+1):(length(array)-1)
for e=(d+1):(length(array)-0)
if array(a)+array(b)+array(c)+array(d)+array(e)=sum_val
fprintf("%i+%i+%i+%i+%i=%i",array(a),array(b),array(c),array(d),array(e),sum_val);
end
end
end
end
end