线性算法是最高效的算法
大O表示法的意义对数据的增长导致时间增长的优劣,更精确的说,大O表示的是增量率,前提是数据sufficiently large
局限就是:数据量的sufficiently large,内存不可能无限大。
brute force algorithm ; worst-case bound ; average-case bound
binary search:
while(low<=high){ int middle = (low+high)/2; if(middle<searchItem) low = middle +1; else if(middle>searchItem) high = middle-1; else return middle; }