Codeforces Round #311 (Div. 2) E. Ann and Half-palindrome (dp+ dictionary tree)

Title Address: Portal
First use DP to find all the matching requirements of the semi-palindrome, marked out. Then construct the dictionary tree. Then DFS again to find out all the nodes of the subtrees, the last search will be able to identify the first K.
The code is as follows:

#include <iostream>#include <string.h>#include <math.h>#include <queue>#include <algorithm>#include <stdlib.h>#include <map>#include <set>#include <stdio.h>#include <time.h>using namespace STD;#define LL __int64#define PI ACOs ( -1.0)//#pragma comment (linker, "/stack:1024000000")Const intMod=1e9+7;Const intinf=0x3f3f3f3f;Const Doubleeqs=1e-9;Const intmaxn=400000+Ten;intok[5001][5001];intK, CNT;Chars[6000], str[6000];structnode{intFlag, sum; Node *next[2];}; Node *newnode () {intI Node *p=NewNode for(i=0;i<2; i++) {p->next[i]=null; } p->flag=0; p->sum=0;returnP;}voidInsert (intStintLen, node *root) {intI, X; Node *p=root; for(i=st;i<len;i++) {x=s[i]-' A ';if(p->next[x]==null) P->next[x]=newnode (); p=p->next[x];if(Ok[st][i])                        {p->flag++;                p->sum++; }        }}voidDFS (node *u) { for(intI=0;i<2; i++) {if(U->next[i]!=null)                        {DFS (u->next[i]);                u->sum+=u->next[i]->sum; }        }}voidSeach (node *root) {node *p=root; while(1) {k-=p->flag;if(k<=0){return; }if(p->next[0]!=null) {if(p->next[0]->sum>=k) {str[cnt]=' A '; p=p->next[0]; cnt++;Continue; }Elsek-=p->next[0]->sum; } str[cnt]=' B '; p=p->next[1];        cnt++; }}intMain () {intI, J, Len, H; while(scanf('%s ', s)!=eof) {scanf("%d", &k); len=strlen(s);memset(OK,0,sizeof(OK)); for(i=0; i<len;i++) {ok[i][i]=1;if(i<len-1&&s[i]==s[i+1]) ok[i][i+1]=1;if(i<len-2&&s[i]==s[i+2]) ok[i][i+2]=1;if(i<len-3&&s[i]==s[i+3]) ok[i][i+3]=1; } for(i=5; i<=len;i++) { for(j=0; j<len-i+1; j + +) {h=j+i-1;if(s[j]==s[h]&&ok[j+2][h-2]) ok[j][h]=1;                }} node *root; Root=newnode (); for(i=0; i<len;i++) {Insert (I, Len, root);                } dfs (root); Cnt=0; Seach (root); for(i=0; i<cnt;i++) {printf("%c", Str[i]); }puts(""); }return 0;}

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Codeforces Round #311 (Div. 2) E. Ann and Half-palindrome (dp+ dictionary tree)