一个人带着一只羊,一条狼和一个白菜想过河,假设他每次只能带一只羊,或者一条狼,或者一棵白菜过河,并限定人不在场时,狼和羊,或羊和白菜不能单独在一起,试编写程序求出他带一只羊,一条狼,一个白菜过河的方法.答案是;#include <stdio.h> #include <stdlib.h> #include <string.h> #define MAX_STEP 20 //index: 0 - 狼,1-羊,2-菜,3-农夫,value:0-本岸,1-对岸 int a[MAX_STEP][4]; int b[MAX_STEP]; char *name[] = { "空手", "带狼", "带羊", "带菜" }; void search(int iStep) { int i; if (a[iStep][0] + a[iStep][1] + a[iStep][2] + a[iStep][3] == 4) { for (i = 0; i < iStep; i++) { if (a[i][3] == 0) { printf("%s到对岸\n", name[b[i] + 1]); } else { printf("%s回本岸\n", name[b[i] + 1]); } } printf("\n"); return; } for (i = 0; i < iStep; i++) { if (memcmp(a[i], a[iStep], sizeof(a[i])) == 0) { return; } } if (a[iStep][1] != a[iStep][3] && (a[iStep][2] == a[iStep][1] || a[iStep][0] == a[iStep][1])) { return; } for (i = -1; i <= 2; i++) { b[iStep] = i; memcpy(a[iStep + 1], a[iStep], sizeof(a[iStep + 1])); a[iStep + 1][3] = 1 - a[iStep + 1][3]; if (i == -1) { search(iStep + 1); } else if (a[iStep][i] == a[iStep][3]) { a[iStep + 1][i] = a[iStep + 1][3]; search(iStep + 1); } } } int main() { search(0); return 0; } 贵求解释.每一步的分析与描述.