BFS DFS （2） 走迷宫 炸弹人

1.走迷宫

迷宫的行n和列m不超过50
广度优先搜索（Breadth First Search, BFS)
用队列模拟这个过程

#include<stdio.h>struct note{    int x;    int y;    int s;};int main(){    struct note que[2501];    int book[51][51]={0};    int a[6][5] = {    {0,0,0,0,0},    {0,0,0,1,0},    {0,0,0,0,0},    {0,0,0,1,0},    {0,0,1,0,0},    {0,0,0,0,1}};    int startx,starty,p,q;    int head,tail,tx,ty,k;    int flag = 0;    int next[4][2] = {{0,1},{1,0},{0,-1},{-1,0}};    //设置起点和终点    do{    printf("请输入起点和终点 如 1 1 4 3表示起点为(1,1),终点为(4,3):\n");    scanf("%d %d %d %d",&startx,&starty,&p,&q);    }while(startx < 1 || startx > 50 || starty < 1 || starty > 50 || p < 1 || p > 50 || q < 1 || q > 50);    //初始化队列    head = 1;    tail = 1;    que[tail].x = startx;    que[tail].y = starty;    que[tail].s = 0;    book[startx][starty] = 1;    tail ++;    //BFS    while(head < tail){        for(k = 0; k<=3; k++){            tx = que[tail].x + next[k][0];            ty = que[tail].y + next[k][1];            if(tx < 1 || tx > 50 || ty < 1 || ty > 50){                continue;            }            if(a[tx][ty] == 0 && book[tx][ty] == 0){                book[tx][ty] = 1;                que[tail].x = tx;                que[tail].y = ty;                que[tail].s = que[head].s + 1;                 tail++;            }            if(tx == p && ty == q){                flag = 1;                break;            }        }        if(flag = 1){            break;        }        head++;    }    printf("从起点到终点要用 %d 步。", que[tail-1].s);    getchar();    getchar();    return 0;}

2.炸弹人

找出哪些点是炸弹人可以到达的。可以用BFS或DFS来枚举出所有小人可以到达的点，然后在这些可以到达的点上分别统计可以消灭的敌人数。

2.0 某个位置消灭敌人个数

int get_num(int x, int y){    int sum,i,j;    i = x;    j = y;    //上    while(a[i[j] != '#'){        if(a[i][j] == 'G'){            sum++;        }        x--;    }    //下    i = x;    j = y;    while(a[i[j] != '#'){        if(a[i][j] == 'G'){            sum++;        }        x++;    }    //左    i = x;    j = y;    while(a[i[j] != '#'){        if(a[i][j] == 'G'){            sum++;        }        y--;    }    //右    i = x;    j = y;    while(a[i[j] != '#'){        if(a[i][j] == 'G'){            sum++;        }        y++;    }    return sum;}

2.1 广度优先搜索

struct note{    int x;    int y;};char a[21][21];int main(){    int book[21][21];    struct note que[401];    int head,tail;    int i,j,k,sum,maxNum = 0,maxX,maxY,n,m,startx,starty,tx,ty;    int next[4][2] = {{0,1},{1,0},{0,-1},{-1,0}}; //右下左上    //地图初始化    scanf("%d %d %d %d",&n,&m,&startx,&starty);    for(i=1;i<=n;i++)        scanf("%s",&a[i]);    //队列初始化    head = 1;    tail = 1;    que[tail].x = startx;    que[tail].y = starty;    tail++;    book[startx][starty] = 1;    maxNum = get_num(startx,starty);    maxX = startx;    maxY = starty;    while(head < tail){        for(k=0;k<=3;k++){            tx = que[head].x + next[k][0];            ty = que[head].y + next[k][1];            //判断越界            if(tx < 1 || tx > n || ty < 1 || ty > m) continue;            if(a[tx][ty] == '.' && book[tx][ty] == 0){                book[tx][ty] = 1;                que[tail].x = tx;                que[tail].y = ty;                tail++;                sum = get_num(tx,ty);                if(sum > maxNum){                    maxNum = sum;                    maxX = tx;maxY = ty;                }            }        }        head++;    }    printf("将炸弹放置在(%d,%d)处，可以消灭%d个敌人。\n",maxX,maxY,maxNum);    getchar();    return 0;}

2.2 深度优先搜索

void bomb_dfs(int x,int y){    int sum,mx,my,k,tx,ty;    book[x][y] = 1;    sum = get_num(x,y);    if(sum > maxNum){        maxX = mx;        maxY = my;        maxNum = sum;    }    for(k = 0;k <= 3;k++){        tx = x + next[k][0];        ty = y + next[k][1];        //判断越界        if(tx < 1 || tx > n || ty < 1 || ty > m) continue;        if(a[tx][ty] == '.' && book[tx][ty]==0){            book[tx][ty] = 1;            bomb_dfs(tx, ty);        }    }    return ;}int main(){    ...    bomb_dfs(startx,starty);    printf("将炸弹放置在(%d,%d)处，可以消灭%d个敌人。\n",maxX,maxY,maxNum);    getchar();    return 0;}