最长公共子序列

<p class="p0"> <span style="font-size:10.5pt;font-family:'Times New Roman';">&nbsp;</span><span style="font-size:10.5pt;font-family:'宋体';">若给定序列<span>X={x1,x2,</span><span>…</span><span>,xm}</span><span>，则另一序列</span><span>Z={z1,z2,</span><span>…</span><span>,zk}</span><span>，是</span><span>X</span><span>的子序列是指存在一个严格递增下标序列</span><span>{i1,i2,</span><span>…</span><span>,ik}</span><span>使得对于所有</span><span>j=1,2,</span><span>…</span><span>,k</span><span>有：</span><span>zj=xij</span><span>。例如，序列</span><span>Z={B</span><span>，</span><span>C</span><span>，</span><span>D</span><span>，</span><span>B}</span><span>是序列</span><span>X={A</span><span>，</span><span>B</span><span>，</span><span>C</span><span>，</span><span>B</span><span>，</span><span>D</span><span>，</span><span>A</span><span>，</span><span>B}</span><span>的子序列，相应的递增下标序列为</span><span>{2</span><span>，</span><span>3</span><span>，</span><span>5</span><span>，</span><span>7}</span><span>。</span></span><span style="font-size:10.5pt;font-family:'Times New Roman';"></span> </p> <p class="p0"> <span style="font-size:10.5pt;font-family:'宋体';">给定<span>2</span><span>个序列</span><span>X</span><span>和</span><span>Y</span><span>，当另一序列</span><span>Z</span><span>既是</span><span>X</span><span>的子序列又是</span><span>Y</span><span>的子序列时，称</span><span>Z</span><span>是序列</span><span>X</span><span>和</span><span>Y</span><span>的公共子序列。</span></span><span style="font-size:10.5pt;font-family:'Times New Roman';"></span> </p> <p class="p0"> <span style="font-size:10.5pt;font-family:'宋体';">给定<span>2</span><span>个序列</span><span>X={x1,x2,</span><span>…</span><span>,xm}</span><span>和</span><span>Y={y1,y2,</span><span>…</span><span>,yn}</span><span>，找出</span><span>X</span><span>和</span><span>Y</span><span>的最长公共子序列。</span></span> </p>

<p> 为保障统计正确，需在输入字符数组x和y的第一个字符设置标示，该字符不参与统计 </p> <p> 第一行输入序列x。 </p> <p> 第二行输入序列y。 </p>

<p> 第一行输出最大子串长度。 </p> <p> 第二行输出最大子串。 </p>