HDU

题意：Y,M两个人要去KFC一起吃个饭，'@'表示KFC。问Y,M每走一步花费11的体力，他俩花费最少的体力为多少？KFC有多个，保证至少有一个KFC是他俩都能到达的。

思路：BFS。两个人都跑一遍地图，存一下每个人到每个点的最小步数。然后从是'@'的点的中求一个最小值。

注意：要把存步数那个数组赋初值为极大值。赋0会wa。因为可能有一个点他俩都到不了，赋0的话最小步数会求一个得0。

#include<bits/stdc++.h>using namespace std;const int INF = 0x3f3f3f;const int MAXN = 205;int n, m;char MAP[MAXN][MAXN];int STEP[2][MAXN][MAXN], dir[4][2] = {{1, 0}, {0, 1}, {-1, 0}, {0, -1}};struct Point{    int x, y, step;}NOW,NEXT;bool vis[MAXN][MAXN];void bfs(int sx, int sy, int people)//people=0，1代表Y，M{    memset(vis, 0, sizeof(vis));    queue<Point> q;    NOW.x = sx; NOW.y = sy; NOW.step = 0; vis[sx][sy] = true;    q.push(NOW);    while (!q.empty())    {        NOW = q.front();        q.pop();        STEP[people][NOW.x][NOW.y] = NOW.step;//记录people步数        for(int i = 0; i < 4; i++)        {            int X = NOW.x + dir[i][0], Y = NOW.y + dir[i][1];            if(X >= 0 && Y >= 0 && X < n && Y < m && MAP[X][Y] != '#' && !vis[X][Y])            {                vis[X][Y] = true;                NEXT.x = X; NEXT.y = Y; NEXT.step = NOW.step + 1;                q.push(NEXT);            }        }    }}int main(){    while (~scanf("%d%d", &n, &m))    {        int x1, x2, y1, y2;        for (int i = 0; i < n; i++)        {            for (int j = 0; j < m; j++)            {                cin >> MAP[i][j];                if(MAP[i][j] == 'Y')                {                    x1 = i; y1 = j;                }                else if(MAP[i][j] == 'M')                {                    x2 = i; y2 = j;                }            }        }        memset(STEP, INF, sizeof(STEP));//步数赋值为极大值，注意memset用法        bfs(x1, y1 ,0);//Y跑一遍图        bfs(x2, y2 ,1);//M跑一遍图        int MIN = INF;//求最小值        for (int i = 0; i < n; i++)        {            for (int j = 0; j < m; j++)            {                if(MAP[i][j] == '@')                {                    MIN = min(MIN, STEP[0][i][j] + STEP[1][i][j]);                }            }        }        printf("%d\n", MIN * 11);    }    return 0;}/*4 4Y.#@.....#..@..M4 4Y.#@.....#..@#.M5 5Y..@..#....#...@..M.#...#*/