uva_10051 - Tower of Cubes(LIS)

这个题目是一个LIS的变形，题目的阶段很明显，就是按照cube的重量分阶段每个阶段的状态：dp[i][k] 表示第i个cube第k个面朝上的最大长度状态转移方程你:dp[i][k] = 1+max{dp[j][z]}, (n >= j > i) （1 <= z,k <= 6)ans = max(dp[i][k]), (1 <= i <= n)#include <cstdio>#include <cstring>#include <algorithm>using namespace std;#define FACE    6#define MAXN    501char conver[][FACE+1] = {         {"front"}, {"back"}, {"left"}, {"right"}, {"top"}, {"bottom"}};typedef struct NODE_ {        int idx, face_idx;}NODE;NODE pre[MAXN][FACE];int dp[MAXN][FACE], color[MAXN][FACE];void back_trace(const int &idx, const int &face_idx){        if( -1 == idx ) {                return;        }        printf("%d %s\n", idx+1, conver[face_idx]);        back_trace(pre[idx][face_idx].idx, pre[idx][face_idx].face_idx);}int dynamic_programming(const int &n){        int rst(0), idx, face_idx, cur_bottom;        memset(dp, 0, sizeof(dp)); memset(pre, -1, sizeof(pre));        for(int i = n-1; i >= 0; i --) {                for(int k = 0; k < FACE; k ++) {                        cur_bottom = (k&1)? k-1 : k+1; dp[i][k] = 1;                        for(int j = n-1; j > i; j --) {                                for(int z = 0; z < FACE; z ++) {                                        if( color[i][cur_bottom] == color[j][z] && dp[i][k] < dp[j][z]+2 ) {                                                dp[i][k] = dp[j][z]+1; pre[i][k].idx = j; pre[i][k].face_idx = z;                                                if( rst < dp[i][k] ) {                                                        rst = dp[i][k]; idx = i; face_idx = k;                                                }                                        }                                }                        }                }        }        printf("%d\n", rst); back_trace(idx, face_idx);}int main(int argc, char const *argv[]){#ifndef ONLINE_JUDGE        freopen("test.in", "r", stdin);#endif        int n, cas(1);        while( scanf("%d", &n) && n ) {                for(int i = 0; i < n; i ++) {                        for(int j = 0; j < FACE; j ++) {                                scanf("%d", &color[i][j]);                        }                }                printf("Case #%d\n", cas ++); dynamic_programming(n); printf("\n");        }        return 0;}