[刷题]算法竞赛入门经典(第2版) 6-4/UVa439 6-5/UVa1600

比较忙比较累，只贴代码了。

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题目：6-4 UVa439 - Knight Moves

//UVa439 - Knight Moves
//Accepted 0.000s
//#define _XIENAOBAN_
#include<iostream>
#include<cstring>
#include<queue>
#define M(po) Map[po.x][po.y]
using namespace std;

struct poi {
    int x, y, weight;
    poi operator +(const poi &that) const {
        return poi{ x + that.x, y + that.y, weight};
    }
    bool operator ==(const poi &that) const {
        return (x == that.x) && (y == that.y);
    }
} op, ed;

const poi dir[8] = { { 2,1 },{ -2,1 },{ 2,-1 },{ -2,-1 },{ 1,2 },{ -1,2 },{ 1,-2 },{ -1,-2 } };
bool Map[10][10];
char xstart, ystart, xend, yend;
int xs, ys, xe, ye;

int BFS(){
    if (op == ed) return 0;
    queue<poi> Q;
    Q.push(op);
    M(op) = true;
    while (!Q.empty()) {
        for (int i(0);i < 8;++i){
            poi nxt(Q.front() + dir[i]);
            if (nxt.x > 0 && nxt.y > 0 && nxt.x < 9 && nxt.y < 9 && !M(nxt)) {
                ++nxt.weight;
                if (nxt == ed) return nxt.weight;
                M(nxt) = true;
                Q.push(nxt);
            }
        }
        Q.pop();
    }
    return -1;
}

int main()
{
#ifdef _XIENAOBAN_
#define gets(T) gets_s(T, 129)
    freopen("in.txt", "r", stdin);
    //freopen("out.txt", "w", stdout);
#endif

    while (scanf("%c%c %c%c", &xstart, &ystart, &xend, &yend) == 4) {
        memset(Map, 0, sizeof(Map));
        op.x = xstart - 96, op.y = ystart - 48, op.weight = 0;
        ed.x = xend - 96, ed.y = yend - 48, ed.weight = 0;
        printf("To get from %c%c to %c%c takes %d knight moves.\n", xstart, ystart, xend, yend, BFS());
        while (getchar() != '\n');
    }
    return 0;
}

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题目：6-5 UVa1600 - Patrol Robot

//UVa1600 - Patrol Robot
//Accepted 0.000s
//#define _XIENAOBAN_
#include<iostream>
#include<cstring>
#include<queue>
#define DONE 2333333
using namespace std;

struct step { int x, y, k, mov; };
int T, m, n, k;
int Map[24][24],Obst[24][24];

void judge(queue<step> &Q, step &now, int x, int y) {
    if (Obst[x += now.x][y += now.y] == DONE) return;
    int _k = (Obst[x][y] ? now.k + 1 : 0);
    if (_k <= k) {
        if (_k) {
            if (Map[x][y] && Map[x][y] <= _k) return;
            Map[x][y] = _k;
        }
        else Obst[x][y] = DONE;
        Q.push(step{ x, y, _k, now.mov + 1 });
    }
}

int main()
{
#ifdef _XIENAOBAN_
#define gets(T) gets_s(T, 129)
    freopen("in.txt", "r", stdin);
    freopen("out.txt", "w", stdout);
#endif

    scanf("%d", &T);
    while (T--) {
        scanf("%d%d%d", &m, &n, &k);
        for (int i(1);i <= m;++i) for (int j(1);j <= n;++j)
            scanf("%d", &Obst[i][j]);
        memset(Map, 0, sizeof(Map));
        queue<step> Q;
        Q.push(step{ 1,1,0,0 });
        Obst[1][1] = DONE;
        while (!Q.empty()) {
            step &now(Q.front());
            if (now.x == m && now.y == n) break;
            if (now.x + 1 <= m) judge(Q, now, 1, 0);
            if (now.y + 1 <= n) judge(Q, now, 0, 1);
            if (now.x - 1 >= 1) judge(Q, now, -1, 0);
            if (now.y - 1 >= 1) judge(Q, now, 0, -1);
            Q.pop();
        }
        if (Q.empty()) printf("-1\n");
        else printf("%d\n", Q.front().mov);
    }
    return 0;
}