php 冒泡排序 快速排序

/******
1)冒泡排序：两两交换数值，最小的值在最左边，就如最轻的气泡在最上边。
2)对整列数两两交换一次，最小的数在最左边，每次都能得一个在剩下的数中的最小 的数，“冒”出来的数组成一个有序区间，剩下的值组成一无序区间，且有序区间中每一元素值都比无序区间的小。
3)快速排序：基准数，左右二个数组，递归调用，合并。
4)插入排序：排序区间分成二部分，左边有序，右边无序，从右区间取第一个元素插入左区间，若此元素比左边区间最右边的元素大，留在原处，若此元素比左 边区间最右边的元素小，则插在最右边5)元素的原位置，同时最右边元素右移一位，计算器减一，重新和前面的元素比较，直到前面的元素比要插入元素小为止，重复 上述步骤。
6)注意区间端点值的处理，及数组的第一个元素下标为0.
***/

<span><br>$a</span>=<span>array</span>('3','8','1','4','11','7'<span>);
</span><span>print_r</span>(<span>$a</span><span>);
</span><span>$len</span> = <span>count</span>(<span>$a</span><span>);
</span><span>//</span><span>从小到大</span><span>for</span>(<span>$i</span>=1;<span>$i</span>$len;<span>$i</span>++<span>)
{
</span><span>for</span>(<span>$j</span>=<span>$len</span>-1;<span>$j</span>>=<span>$i</span>;<span>$j</span>--<span>)
</span><span>if</span>(<span>$a</span>[<span>$j</span>]$a[<span>$j</span>-1<span>])
{</span><span>//</span><span>如果是从大到小的话，只要在这里的判断改成if($b[$j]>$b[$j-1])就可以了</span><span>$x</span>=<span>$a</span>[<span>$j</span><span>];
 </span><span>$a</span>[<span>$j</span>]=<span>$a</span>[<span>$j</span>-1<span>];
 </span><span>$a</span>[<span>$j</span>-1]=<span>$x</span><span>;
}
}
</span><span>print_r</span>(<span>$a</span><span>);
</span><span>//</span><span>另一种方法 从小到大</span><span>$b</span>=<span>array</span>('4','3','8','9','2','1'<span>);
</span><span>$len</span>=<span>count</span>(<span>$b</span><span>);
</span><span>for</span>(<span>$k</span>=1;<span>$k</span>$len;<span>$k</span>++<span>)
{
</span><span>for</span>(<span>$j</span>=<span>$len</span>-1,<span>$i</span>=0;<span>$i</span>$len-<span>$k</span>;<span>$i</span>++,<span>$j</span>--<span>)
</span><span>if</span>(<span>$b</span>[<span>$j</span>]$b[<span>$j</span>-1<span>]){
</span><span>//</span><span>如果是从大到小的话，只要在这里的判断改成if($b[$j]>$b[$j-1])就可以了</span><span>$tmp</span>=<span>$b</span>[<span>$j</span><span>];
 </span><span>$b</span>[<span>$j</span>]=<span>$b</span>[<span>$j</span>-1<span>];
 </span><span>$b</span>[<span>$j</span>-1]=<span>$tmp</span><span>;
}
</span><span>print_r</span>(<span>$b</span><span>);
</span><span>echo</span> "
"<span>;
}
</span><span>//</span><span>下面的这个执行效率更高</span><span>function</span> maopao(<span>$arr</span><span>)
{
 </span><span>$len</span> = <span>count</span>(<span>$arr</span><span>);
 </span><span>for</span>(<span>$i</span>=1; <span>$i</span>$len; <span>$i</span>++)<span>//</span><span>最多做n-1趟排序</span><span> {
  </span><span>$flag</span> = <span>false</span>;    <span>//</span><span>本趟排序开始前，交换标志应为假</span><span>for</span>(<span>$j</span>=<span>$len</span>-1;<span>$j</span>>=<span>$i</span>;<span>$j</span>--<span>)
  {
   </span><span>if</span>(<span>$arr</span>[<span>$j</span>]$arr[<span>$j</span>-1])<span>//</span><span>交换记录</span>   {<span>//</span><span>如果是从大到小的话，只要在这里的判断改成if($arr[$j]>$arr[$j-1])就可以了</span><span>$x</span>=<span>$arr</span>[<span>$j</span><span>];
     </span><span>$arr</span>[<span>$j</span>]=<span>$arr</span>[<span>$j</span>-1<span>];
     </span><span>$arr</span>[<span>$j</span>-1]=<span>$x</span><span>;
     </span><span>$flag</span> = <span>true</span>;<span>//</span><span>发生了交换，故将交换标志置为真</span><span>   }
  }
  </span><span>if</span>(! <span>$flag</span>)<span>//</span><span>本趟排序未发生交换，提前终止算法</span><span>return</span><span>$arr</span><span>;   
 }
}
</span><span>$shuz</span> = <span>array</span>('2','4','1','8','5'<span>);
</span><span>$bb</span> = maopao(<span>$shuz</span><span>);
</span><span>print_r</span>(<span>$bb</span><span>);
</span><span>//</span><span> 快速排序</span><span>function</span> kuaisu(<span>$arr</span><span>){
    </span><span>$len</span> = <span>count</span>(<span>$arr</span><span>);
    </span><span>if</span>(<span>$len</span> ){
        <span>return</span><span>$arr</span><span>;
    }
    </span><span>$key</span> = <span>$arr</span>[0<span>];
    </span><span>$left_arr</span> = <span>array</span><span>();
    </span><span>$right_arr</span> = <span>array</span><span>();
    </span><span>for</span>(<span>$i</span>=1; <span>$i</span>$len;<span>$i</span>++<span>){
        </span><span>if</span>(<span>$arr</span>[<span>$i</span>] $key<span>){
            </span><span>$left_arr</span>[] = <span>$arr</span>[<span>$i</span><span>];
        }</span><span>else</span><span>{
            </span><span>$right_arr</span>[] = <span>$arr</span>[<span>$i</span><span>];
        }
    }
    </span><span>$left_arr</span> = kuaisu(<span>$left_arr</span><span>);
    </span><span>$right_arr</span> = kuaisu(<span>$right_arr</span><span>);
    </span><span>return</span><span>array_merge</span>(<span>$left_arr</span>, <span>array</span>(<span>$key</span>), <span>$right_arr</span><span>);
}
</span><span>$arr</span> = <span>array</span>(23,98,54,2,9,62,34<span>);
</span><span>print_r</span>(kuaisu(<span>$arr</span>));

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