题目地址：http://vjudge.net/problem/UVA-11404
一开始以为是逆序后再求 LICS ， 完全不知道怎么做
然而 只是个 逆序后求 最长且字典序最小的 公共子序列
#include <bits/stdc++.h>
using namespace std;
#define REP(i,a,b) for(int i=a;i<=(int)(b);++i)
#define REPD(i,a,b) for(int i=a;i>=(int)(b);--i)
const int maxn=1000+5;
struct Node
{int len; string s;bool operator < (const Node& n) const {return len == n.len ? s<n.s : len>n.len;}
}d[maxn][maxn];
string s,rs;
int main(int argc, char const *argv[])
{while(cin>>s){rs=s; reverse(rs.begin(), rs.end());s='.'+s; rs='.'+rs;int len=s.length();REP(i,0,len) {d[0][i].len=d[i][0].len=0;d[0][i].s.clear(); d[i][0].s.clear();}REP(i,1,len) REP(j,1,len) {if(s[i]==rs[j]) {d[i][j].len=d[i-1][j-1].len+1;d[i][j].s=d[i-1][j-1].s+s[i];}else d[i][j]=min(d[i-1][j],d[i][j-1]);}int MaxLen=d[len][len].len-1;string MaxS=d[len][len].s;if(MaxLen&1) {REP(i,0,MaxLen/2-1) cout<<MaxS[i];REPD(i,MaxLen/2,0) cout<<MaxS[i];}else {REP(i,0,MaxLen/2-1) cout<<MaxS[i];REPD(i,MaxLen/2-1,0) cout<<MaxS[i];}printf("\n");}return 0;
}