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UVA10618 跳舞机 Tango Tango Insurrection

有四个踩踏板，不同的踩踏方式消耗不同的力气

问最小花费的力气

F[ i ] [ a] [b ][ s] ， s 是上一次哪只角移动了( 0 ,1,2 )

https://www.luogu.com.cn/problem/UVA10618

100

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107

#include<iostream>
#include <cstring>
#include <algorithm>
const int N =1003;
#define inf 1e9
#define UP 0
#define LEFT 1
#define RIGHT 2
#define DOWN 3
 
char str[N] ,opt[]=".LR";
int n,f[N][5][5][3], op[N][4][4][3];
 
 
int get(int a,int b){
    if(a == b) return 3;
    if(a+b == 3) return 7;
    return 5;
}
int energy(int i,int a,int b,int s,int g,int t,int &ta,int &tb){
    ta=a,tb=b;
    if(g == 1) ta=t;
    else if(g == 2) tb=t;
 
    if(ta == tb) return -1;
    if(ta == RIGHT && tb == LEFT) return -1;
    if(a == RIGHT && tb != b) return -1;
    if(b == LEFT && ta != a) return -1;
 
    int res;
    if(g == 0) res=0;
    else if(g != s) res=1;
    else{
        if(g == 1) res=get(a,ta);
        else res=get(b,tb);
    }
    return res;
}
 
void mov(int i,int a,int b,int s,int g,int t){
    int ta,tb;
    int E=energy(i,a,b,s,g,t,ta,tb);
    if(E < 0) return;
    int cost=f[i+1][ta][tb][g]+E;
    int &v=f[i][a][b][s];
    if(cost < v){
        v=cost;
        op[i][a][b][s]=g*4+t;
    }
}
void sov(){
    int i ,a,b; 
    for(i=n-1;i>=0;i--)
     for(a=0;a<4;a++)
      for(b=0;b<4;b++)
         if(a!=b) {
             
            for(int s=0;s<3;s++){
                 f[i][a][b][s] = inf ;
            if(str[i]=='.'){
                mov(i,a,b,s,0,0) ;
                for(int t=0;t<4;t++){
                    mov(i,a,b,s,1,t);
                    mov(i,a,b,s,2,t);
                }
            }
            else{
                if(str[i]=='U'){
                    mov(i,a,b,s,1,0);
                    mov(i,a,b,s,2,0);
                }
                else if(str[i]=='L'){
                    mov(i,a,b,s,1,1) ;
                    mov(i,a,b,s,2,1);
                }
                else if(str[i]=='R'){
                    mov(i,a,b,s,1,2);
                    mov(i,a,b,s,2,2);
                }
                else{
                    mov(i,a,b,s,1,3) ;
                    mov(i,a,b,s,2,3) ;
                }
            }
          }
         }
}
signed main () {
    while(std::cin>>str){
        if(str[0] == '#') break;
        n=strlen(str);
        memset(f,0,sizeof f);
 
        sov();
 
        int a=LEFT,b=RIGHT,s=0;
        for(int i=0;i<n;++i){
            int g=op[i][a][b][s]/4;
            int t=op[i][a][b][s]%4;
            printf("%c",opt[g]);
            s=g;
            if(g == 1) a=t;
            else if(g == 2) b=t;
        }
        puts("");
    }
} 