Submission #131916

#	Time	Username	Problem	Language	Result	Execution time	Memory
131916		dragonslayerit	Linear Garden (IOI08_linear_garden)	C++14	100 / 100	180 ms	46396 KiB

linear_garden

#include <cstdio>
#include <cassert>

char str[1000005];
int MOD;

struct State{
  char max,curr;
  State(char max,char curr):max(max),curr(curr){
    assert(curr>=0&&curr<=max);
  }
  State up()const{
    return (curr==max)?State(max+1,max+1):State(max,curr+1);
  }
  State down()const{
    return (curr==0)?State(max+1,0):State(max,curr-1);
  }
};

int memo[1000005][9];
bool vis[1000005][9];

int complete(State prefix,int len){
  if(prefix.max>2) return 0;
  if(len==0) return 1;
  int code=prefix.max*3+prefix.curr;
  if(vis[len][code]) return memo[len][code];
  vis[len][code]=true;
  return memo[len][code]=(complete(prefix.up(),len-1)+complete(prefix.down(),len-1))%MOD;
}

int main(){
  int N;
  scanf("%d %d",&N,&MOD);
  scanf("%s",str);
  int ans=1;
  State prefix(0,0);
  for(int i=0;i<N;i++){
    for(int s=0;s<3;s++){
      for(int t=0;t<=s;t++){
	complete(State(s,t),i);
      }
    }
  }
  for(int i=0;i<N;i++){
    if(str[i]=='P'){
      ans=(ans+complete(prefix.down(),N-i-1))%MOD;
      prefix=prefix.up();
    }else{
      prefix=prefix.down();
    }
  }
  printf("%d\n",ans);
  return 0;
}

Compilation message (stderr)

linear_garden.cpp: In function 'int main()':
linear_garden.cpp:34:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d %d",&N,&MOD);
   ~~~~~^~~~~~~~~~~~~~~~~
linear_garden.cpp:35:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%s",str);
   ~~~~~^~~~~~~~~~

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