Woj 1574-k-th Smallest divided treatment

Poke here: 1574

Test instructions: Remove any number from an n-length number to find out what number of K is large.

Official solution: Removing the remaining numbers after Ri is obviously either larger than removing any RJ (J > I), or smaller than removing any RJ. So first sweep from the back to the pre-processing after removing the RI is larger or smaller than the back. Then divide and conquer it.

WHU Invitational A question, at that time did not think out solution, read the problem wrote a bit on AC ...

1#include"bits/stdc++.h"2 using namespacestd;3 intN, K;4 Charans[1000010];5 //Rank_suffix[i] means that the new number formed by removing the number i is the suffix I of the original string minus a number of the new number formed in the set is the first rank_suffix[i] small6 intrank_suffix[1000010];7 8 intMain ()9 {Tenans[0] ='0'-1; One      while(SCANF ("%d%d", &n, &k)! =EOF) { Ascanf"%s", ans +1); -         inti; -Rank_suffix[n] =1; the          for(i = n-1; I >=1; --i) { -             //The current number is the largest number on the set corresponding to the suffix i -             if(Ans[i +1] >Ans[i]) { -Rank_suffix[i] = n-i +1; +             } -             //It can be thought that when the numbers are as large as possible, the numbers that are removed from the preceding numbers are larger. +             Else if(Ans[i +1] ==Ans[i]) { ARank_suffix[i] = rank_suffix[i +1] +1; at             } -             //Ans[i + 1] < Ans[i], the current number is the smallest on the set corresponding to the suffix i -             Else{ -Rank_suffix[i] =1; -             } -         } in  -         //divide and conquer, beg K small to         intres =1; +          for(i =1; I <= N; ++i) { -             if(Ans[i]! = ans[i-1]) { the                 //Res is used to record the position of the first occurrence of the newly formed number, the time delay marker *res =i; $             }Panax Notoginseng             //Divide and conquer the end -             if(Rank_suffix[i] = =k) { the                  Break; +             } A             if(Rank_suffix[i] <k) { the--K; +             } -         } $printf"%d\n", res); $     } -}

Woj 1574-k-th Smallest divided treatment