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uva 1352 - Colored Cubes

 
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链接:

http://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&category=456&page=show_problem&problem=4098


刘汝佳书上的例题(训练指南P16),感觉这题很好,尤其是生成旋转序列的方法,这也是这题的重点。学习了。


#include<cstdio>
#include<cstring>
#include<map>
#include<set>
#include<string>
using namespace std;

map<string,int>color;
int cube[5][6];
int now[5][6];
int n, ans;
int p[7];
int cnt[25];

int dice24[24][6] = {
3,1,0,5,4,2,
1,2,0,5,3,4,
2,4,0,5,1,3,
4,3,0,5,2,1,
3,5,1,4,0,2,
5,2,1,4,3,0,
2,0,1,4,5,3,
0,3,1,4,2,5,
0,1,2,3,4,5,
1,5,2,3,0,4,
5,4,2,3,1,0,
4,0,2,3,5,1,
5,1,3,2,4,0,
1,0,3,2,5,4,
0,4,3,2,1,5,
4,5,3,2,0,1,
3,4,5,0,1,2,
4,2,5,0,3,1,
2,1,5,0,4,3,
1,3,5,0,2,4,
3,0,4,1,5,2,
0,2,4,1,3,5,
2,5,4,1,0,3,
5,3,4,1,2,0,
};

int left[] = {1,5,2,3,0,4};
int up[] = {3,1,0,5,4,2};

// “旋转”
void rot(int* T, int* p){
    int q[6];
    memcpy(q,p,sizeof(q));
    for(int i=0; i<6; ++i) p[i] = q[T[i]];
}
// 生成旋转序列用的
void func(){ 
    int p0[6] = {0,1,2,3,4,5};
    printf("int dice24[24][6] = {\n");
    for(int i=0; i<6; ++i) {
        int p[6];
        memcpy(p, p0, sizeof(p0));
        if(i==0) rot(up, p);
        if(i==1) { rot(left,p); rot(up, p); }
        if(i==3) { rot(up,p); rot(up, p); }
        if(i==4) { rot(left, p); rot(left,p); rot(up,p); }
        if(i==5) { rot(left, p); rot(left,p); rot(left,p); rot(up,p);}
        for(int j=0; j<4; ++j){
            printf("%d,%d,%d,%d,%d,%d,\n",p[0],p[1],p[2],p[3],p[4],p[5]);
            rot(left,p);
        }
        
    }
    printf("};\n");
}

// dfs暴力答案
void dfs(int cur){
    if(cur>=n){
        int counter=0;
        for(int i=0; i<6; ++i) {
            memset(cnt, 0, sizeof(cnt));
            int tmp=0;
            for(int j=0; j<n; ++j){
                tmp = max(tmp, ++cnt[now[j][i]]);
            }
            counter += n-tmp;
        }
        ans = min(counter, ans);
        return;
    }
    for(int i=0; i<24; ++i){
        for(int j=0; j<6; ++j)
            now[cur][j] = cube[cur][dice24[i][j]];
        dfs(cur+1);
    }
}

int main(){
    char c[30];
    int idx;

    while(~scanf("%d", &n) && n){
        
        idx=0;
        color.clear();
        for(int i=0; i<n; ++i){
            for(int j=0; j<6; ++j) {
                scanf("%s", c);
                if(color.find(c) == color.end()){
                    color[c] = ++idx;
                }
                cube[i][j] = color[c];
            }
        }
        ans = 10000000;
        for(int i=0; i<6; ++i) now[0][i]=cube[0][i];
        dfs(1);
        printf("%d\n", ans);
    }

    return 0;
}



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