"USACO1.1" Broken necklace

Test instructions

A ring necklace, there are rbw three kinds of beads, R for Red,b on behalf of the BLUE,W on behalf of White, from any position, the two ends take beads, the same end of the beads to the same color, W can be dyed to the desired color, that can be used as r can also be used as B, the maximum number of beads obtained. A maximum of 350 beads.

Analysis

You can enumerate the broken positions and then simulate the beads. You can also raise the position of a point. You can also do DP.

Code

Enumerate breakpoints

#include<cstdio> 
#include<algorithm> 
#Define N 355 
using namespace STD;

CharA
intB[n];
intN,ans;

 int solve(int p,int dir) //p is the starting point, dir is the direction and the maximum number of
{
    intlen=0;//number of beads taken, up to n beads

     for(intJ=p+n; len<n; Len++,j+=dir)//j is the current position +n, the current position is j%n
{
        if(B[p] && b[j%n] && b[j%n]!=b[p])
             Break;
        if(!b[p])//Every time the beads are in accordance with the color of the P position, if the P position is w, it is necessary to update P
p=j%n;
}
    returnLen
}
 int main()
{
    scanf("%d", &n);
     for(intI=0; i<n; i++)
{
A=getchar ();
b[i]=a==' B '?1: a==' R '?2:0;//b--1 r--2 w--0
}
     for(intI=0; i<n; i++)//Enumerate breakpoints
Ans=max (Ans,solve (i,-1) +solve (i+1,1));
Ans=min (Ans,n);//may have been calculated two times, but only in the case of all
    printf("%d\n", ans);
    return 0;
}

a lift.

#include<cstdio> 
#include<algorithm> 
#include<iostream> 
#include<string> 
using namespace STD;
intN,ans;
stringS
 int main()
{
    Cin>>n>>s;
S+=s;
     for(intI=0, J; i<n; i++)//With I for the beginning of the first paragraph, not the cutting position
{
        CharNow=s[i];
        intlen=0;
        inttimes=now==' W '?3:2;//If the current is white, then need to find three pieces of the same color or find two paragraph
J=i;
         while(times--)
{
             while(j<i+n&& (s[j]==now| | s[j]==' W '))
{
len++;
j + +;
}
NOW=S[J];
}
Ans=max (Ans,len);
}
    cout<<ans<<endl;
    return 0;
}

Dp

#include<cstdio> 
#include<iostream> 
#include<algorithm> 
#include<string> 
#define N 720 
using namespace STD;
intN,ans;
stringS
intl[n][2],r[n][2];
 int main() {
    Cin>>n>>s;
S+=s;
     for(intI=1;i<2*n;i++) {
l[i][0]=l[i-1][0]+1;
l[i][1]=l[i-1][1]+1;
        if(s[i-1]==' R ')
l[i][1]=0;
        Else if(s[i-1]==' B ')
l[i][0]=0;
}
     for(intI=2*n-1; i>=0; i--) {
r[i][0]=r[i+1][0]+1;
r[i][1]=r[i+1][1]+1;
        if(s[i]==' R ')
r[i][1]=0;
        Else if(s[i]==' B ')
r[i][0]=0;
}
     for(intI=0;i<2*n;i++)
Ans=max (Ans,max (l[i][0],l[i][1]) +max (r[i][0],r[i][1]));
Ans=min (Ans,n);
    cout<<ans<<endl;
    return 0;
}

"USACO1.1" Broken necklace