USACO算法系列十六——camelot

   题目：http://www.nocow.cn/index.php/Translate:USACO/camelot

   题目挺好理解的，但是没有清晰的思路，只靠不断的模拟，目前USACO里面，我写过的最长的算法程序。而且还没通过，各种抓狂中……

   先插代码，实在没有很好的想法，悲剧啊，难到这就是局限了。欢迎大家给意见

#include <iostream>#include <fstream>#include <math.h>#define ROW 31#define COLUMN 27#define SIZE 780#define LARGE 0X7FFFFFFF#define KNIGHT 800#define KING 900using namespace std;struct Position{int r;int c; };//棋盘int R,C;int grid[ROW][COLUMN] = {0};//骑士Position knight[SIZE];int knightload[SIZE]; //骑士所走过的路的长度int kl;int result = LARGE;//国王Position king;int kingtoknight[SIZE]; //骑士到国王的距离bool flag = false;Position knightk; //国王到最近骑士的距离int kntok = LARGE;//国王到最近骑士的距离//记录遍历路径Position path[SIZE];int pl = 0;//初始化整个棋盘void initGrid(){for (int i=1; i <= R; i++){for (int j=1; j <= C;j ++){grid[i][j] = 0;}//end j}//end igrid[king.r][king.c] = KING;for (int i =0; i < kl; i ++ ){grid[knight[i].r][knight[i].c] = KNIGHT;}//end i}int getKnight(int r,int c){for (int i=0; i < kl; i ++){if (knight[i].r == r && knight[i].c == c){return i;}//end if}return -1;}int main(){ifstream fin("camelot.in");ofstream fout("camelot.out");char column;//读入数据fin >> R >> C;//读入国王fin >> column >> king.r;king.c = column - 'A' + 1;grid[king.r][king.c] = KING;//读入骑士while (!fin.eof()){fin >> column >> knight[kl].r;if (knight[kl].r != 0){knight[kl].c = column - 'A' + 1;if (grid[knight[kl].r][knight[kl].c] == KING){//国王其实在同一个位置grid[knight[kl].r][knight[kl].c] = KNIGHT;flag = true;}else{grid[knight[kl].r][knight[kl].c] = KNIGHT;}kl ++;}}//end whileif (kl == 0){fout << 0 << endl;return 0;}if(!flag){//广度遍历国王到最短的骑士,按照骑士走法path[0] = king;pl ++;int klnumber = 0;grid[king.r][king.c] = 0;for (int i=0; i < pl; i ++){int r = path[i].r;int c = path[i].c;//左斜上if (r > 1 && c > 2 ){if (grid[r-1][c-2] == 0){path[pl].r = r -1;path[pl].c = c -2;grid[r-1][c-2] = grid[r][c] + 1;pl ++;}//end ifelse if(grid[r-1][c-2] == KNIGHT){path[pl].r = r -1;path[pl].c = c -2;pl ++;int index = getKnight(r-1,c-2);kingtoknight[index] = grid[r][c] + 1;grid[r-1][c-2] = grid[r][c] + 1;klnumber ++;}//end elseif (klnumber == kl){break;}}//左上if (r > 2 && c > 1){if (grid[r-2][c-1] == 0){path[pl].r = r -2;path[pl].c = c -1;grid[r-2][c-1] = grid[r][c] + 1;pl ++;}//end ifelse if(grid[r-2][c-1] == KNIGHT){path[pl].r = r -2;path[pl].c = c -1;pl ++;int index = getKnight(r-2,c-1);kingtoknight[index] = grid[r][c] + 1;grid[r-2][c-1] = grid[r][c] + 1;klnumber ++;}//end elseif (klnumber == kl){break;}}//右上if (r > 2 && c + 1 <= C){if (grid[r-2][c+1] == 0){path[pl].r = r - 2;path[pl].c = c+ 1;grid[r-2][c+1] = grid[r][c] + 1;pl ++;}//end ifelse if(grid[r-2][c+1] == KNIGHT){path[pl].r = r - 2;path[pl].c = c+ 1;pl ++;int index = getKnight(r-2,c+1);kingtoknight[index] = grid[r][c] + 1;grid[r-2][c+1] = grid[r][c] + 1;klnumber ++;}//end elseif (klnumber == kl){break;}}//右斜上if (r > 1 && c + 2 <= C){if (grid[r-1][c+2] == 0){path[pl].r = r - 1;path[pl].c = c+ 2;grid[r-1][c+2] = grid[r][c] + 1;pl ++;}//end ifelse if (grid[r-1][c+2] ==KNIGHT){path[pl].r = r - 1;path[pl].c = c+ 2;pl ++;int index = getKnight(r-1,c+2);kingtoknight[index] = grid[r][c] + 1;grid[r-1][c+2] = grid[r][c] + 1;klnumber ++;}//end elseif (klnumber == kl){break;}}//右斜下if (r + 1 <= R && c + 2 <= C){if (grid[r+1][c+2] == 0){path[pl].r = r +1;path[pl].c = c+ 2;grid[r+1][c+2] = grid[r][c] + 1;pl ++;}//end ifelse if(grid[r+1][c+2]==KNIGHT){path[pl].r = r +1;path[pl].c = c+ 2;pl ++;int index = getKnight(r+1,c+2);kingtoknight[index] = grid[r][c] + 1;grid[r+1][c+2] = grid[r][c] + 1;klnumber ++;}//end elseif (klnumber == kl){break;}}//右下if (r + 2 <= R && c + 1 <= C){if (grid[r+2][c+1] == 0){path[pl].r = r +2;path[pl].c = c+ 1;grid[r+2][c+1] = grid[r][c] + 1;pl ++;}//end ifelse if(grid[r+2][c+1] == KNIGHT){path[pl].r = r +2;path[pl].c = c+ 1;pl ++;int index = getKnight(r+2,c+1);kingtoknight[index] = grid[r][c] + 1;grid[r+2][c+1] = grid[r][c] + 1;klnumber ++;}//end elseif (klnumber == kl){break;}}//左下if (r + 2 <= R && c - 1 >0){if (grid[r+2][c-1] == 0){path[pl].r = r +2;path[pl].c = c- 1;grid[r+2][c-1] = grid[r][c] + 1;pl ++;}//end ifelse if (grid[r+2][c-1] ==KNIGHT){path[pl].r = r +2;path[pl].c = c- 1;pl ++;int index = getKnight(r+2,c-1);kingtoknight[index] = grid[r][c] + 1;grid[r+2][c-1] = grid[r][c] + 1;klnumber ++;}//end elseif (klnumber == kl){break;}}//左斜下if (r + 1 <= R && c - 2 >0){if (grid[r+1][c-2] == 0){path[pl].r = r +1;path[pl].c = c- 2;grid[r+1][c-2] = grid[r][c] + 1;pl ++;}//end ifelse if (grid[r+1][c-2] == KNIGHT){path[pl].r = r +1;path[pl].c = c- 2;pl ++;int index = getKnight(r+1,c-2);kingtoknight[index] = grid[r][c] + 1;grid[r+1][c-2] = grid[r][c] + 1;klnumber ++;}//end elseif (klnumber == kl){break;}}}//end for}//end if !flag//国王到骑士的路径for (int i=0; i < kl; i ++ ){int absr = abs(knight[i].r - king.r);int absc = abs(knight[i].c - king.c);int temp = max(absr,absc);if (temp < kntok){kntok = temp;knightk.r = knight[i].r;knightk.c = knight[i].c;}//end if}//end for//遍历整个棋盘for(int i=1; i <= R; i ++){for (int j=1; j <= C; j ++){initGrid();path[0].r = i;path[0].c = j;pl = 1;int number = 0;if (grid[i][j] == KNIGHT){number ++;}if (i == king.r && j == king.c){number ++;}grid[i][j] = 1;//广度遍历到所有骑士for (int k=0; k < pl; k ++ ){int r = path[k].r;int c = path[k].c;//左斜上if (r > 1 && c > 2 ){if (grid[r-1][c-2] == 0){path[pl].r = r -1;path[pl].c = c -2;grid[r-1][c-2] = grid[r][c] + 1;pl ++;}//end ifelse if(grid[r-1][c-2] == KNIGHT||grid[r-1][c-2] == KING){path[pl].r = r -1;path[pl].c = c -2;grid[r-1][c-2] = grid[r][c] + 1;number ++;pl ++;}//end elseif (number == kl + 1){break;}}//左上if (r > 2 && c > 1){if (grid[r-2][c-1] == 0){path[pl].r = r -2;path[pl].c = c -1;grid[r-2][c-1] = grid[r][c] + 1;pl ++;}//end ifelse if(grid[r-2][c-1] == KNIGHT||grid[r-2][c-1] == KING){path[pl].r = r -2;path[pl].c = c -1;grid[r-2][c-1] = grid[r][c] + 1;number ++;pl ++;}//end elseif (number == kl + 1){break;}}//右上if (r > 2 && c + 1 <= C){if (grid[r-2][c+1] == 0){path[pl].r = r - 2;path[pl].c = c+ 1;grid[r-2][c+1] = grid[r][c] + 1;pl ++;}//end ifelse if(grid[r-2][c+1] == KNIGHT||grid[r-2][c+1] == KING){path[pl].r = r - 2;path[pl].c = c+ 1;grid[r-2][c+1] = grid[r][c] + 1;number ++;pl ++;}//end elseif (number == kl + 1){break;}}//右斜上if (r > 1 && c + 2 <= C){if (grid[r-1][c+2] == 0){path[pl].r = r - 1;path[pl].c = c+ 2;grid[r-1][c+2] = grid[r][c] + 1;pl ++;}//end ifelse if(grid[r-1][c+2] == KNIGHT||grid[r-1][c+2] == KING){path[pl].r = r - 1;path[pl].c = c+ 2;grid[r-1][c+2] = grid[r][c] + 1;number ++;pl ++;}//end elseif (number == kl + 1){break;}}//右斜下if (r + 1 <= R && c + 2 <= C){if (grid[r+1][c+2] == 0){path[pl].r = r +1;path[pl].c = c+ 2;grid[r+1][c+2] = grid[r][c] + 1;pl ++;}//end ifelse if(grid[r+1][c+2] == KNIGHT||grid[r+1][c+2] == KING){path[pl].r = r +1;path[pl].c = c+ 2;grid[r+1][c+2] = grid[r][c] + 1;number ++;pl ++;}//end elseif (number == kl + 1){break;}}//右下if (r + 2 <= R && c + 1 <= C){if (grid[r+2][c+1] == 0){path[pl].r = r +2;path[pl].c = c+ 1;grid[r+2][c+1] = grid[r][c] + 1;pl ++;}//end ifelse if(grid[r+2][c+1] == KNIGHT||grid[r+2][c+1] == KING){path[pl].r = r +2;path[pl].c = c+ 1;grid[r+2][c+1] = grid[r][c] + 1;number ++;pl ++;}//end elseif (number == kl + 1){break;}}//左下if (r + 2 <= R && c - 1 >0){if (grid[r+2][c-1] == 0){path[pl].r = r +2;path[pl].c = c- 1;grid[r+2][c-1] = grid[r][c] + 1;pl ++;}//end ifelse if(grid[r+2][c-1] == KNIGHT||grid[r+2][c-1] == KING){path[pl].r = r +2;path[pl].c = c- 1;grid[r+2][c-1] = grid[r][c] + 1;number ++;pl ++;}//end elseif (number == kl + 1){break;}}//左斜下if (r + 1 <= R && c - 2 >0){if (grid[r+1][c-2] == 0){path[pl].r = r +2;path[pl].c = c+ 1;grid[r+1][c-2] = grid[r][c] + 1;pl ++;}//end ifelse if(grid[r+1][c-2] == KNIGHT||grid[r+1][c-2] == KING){path[pl].r = r +2;path[pl].c = c+ 1;grid[r+1][c-2] = grid[r][c] + 1;number ++;pl ++;}//end elseif (number == kl + 1){break;}}}//end forbool tempflag = false;int tempresult =0 ;//判断国王是否在骑士到集结地的路上for (int m=0; m< kl; m++ ){int tempking = grid[king.r][king.c];if (tempking + kingtoknight[m] == grid[knight[m].r][knight[m].c]){tempflag = true;}tempresult += grid[knight[m].r][knight[m].c] -1;}//end forif (tempflag || flag){if (tempresult < result){result = tempresult;}}else{int minload = LARGE;int minindex = -1;for (int i=0; i<kl; i ++){if (minload > kingtoknight[i]){minload = kingtoknight[i];minindex = i;}//end if}//end forint tempresult2 = tempresult + minload - grid[knight[i].r][knight[i].c] + grid[king.r][king.c];if (tempresult2 < result){result = tempresult2;}int tempresult3 = tempresult + kntok;if (tempresult3 < result){result = tempresult3;}int absr = abs( knight[i].r - i );int absc = abs( knight[i].c - j );int tempresult4 = max(absr,absc) + tempresult;if (tempresult4 < result){result = tempresult4;}}}//end j}//end ifout << result << endl;return 0;}