UVa227-Puzzle

题目链接： https://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&page=show_problem&problem=163#include <iostream>
#include <cstdio>
#include <cstring>
#include <string>
#include <vector>
#include <map>
#include <string>
#include <algorithm>
#include <functional>
#include <cctype>
#include <cassert>
#define _for(i,a,b) for(int i = (a); i < (b); ++i)
#define _rep(i,a,b) for(int i = (a); i <= (b); ++i)
using namespace std;

struct Point {
int x, y;
Point(int x = 0, int y = 0) :x(x), y(y) {}
};

Point operator + (const Point &A, const Point &B) { return Point(A.x + B.x, A.y + B.y); }
Point operator - (const Point &A, const Point &B) { return Point(A.x - B.x, A.y - B.y); }
Point operator * (const Point &A, int p) { return Point(A.x * p, A.y * p); }
Point operator / (const Point &A, int p) { return Point(A.x / p, A.y / p); }
bool operator == (const Point &A, const Point &B) { return (A.x == B.x && A.y == B.y); }
bool operator < (const Point &A, const Point &B) { return A.x < B.x || (A.x == B.x && A.y < B.y); }

const int GSize = 5;
vector<string> grid;
Point ePos;
map<char, Point> DIRS = { { 'A',Point(-1, 0) },{ 'B',Point(1, 0) },{ 'L',Point(0, -1) },{ 'R',Point(0, 1) }, };
bool valid(const Point& p) { return p.x >= 0 && p.x < GSize && p.y >= 0 && p.y < GSize; }

void printGrid() {
_for(i, 0, GSize) {
_for(j, 0, GSize) {
if (j) cout << ' ';
cout << grid[i][j];
}
cout << endl;
}
}

bool tryMove(char cmd) {
if (!DIRS.count(cmd)) return false;
assert(DIRS.count(cmd));
Point P = ePos + DIRS[cmd];
if (!valid(P)) return false;
swap(grid[P.x][P.y], grid[ePos.x][ePos.y]);
ePos = P;
return true;
}

int main() {
#ifdef LOCAL
freopen("Text.txt", "r", stdin);
#endif
int t = 1;
string line;
while (true) {
grid.clear();
ePos.x = -1; ePos.y = -1;
_for(i, 0, GSize) {
getline(cin, line);
if (line == "Z") return 0;
assert(line.size() == GSize);
_for(j, 0, GSize) {
if (line[j] != ' ') continue;
assert(ePos.x == -1 && ePos.y == -1);
ePos.x = i;
ePos.y = j;
}
grid.push_back(line);
}
string moves;
while (true) {
getline(cin, line);
assert(!line.empty());
bool end = *(line.rbegin()) == '0';
if (!end) moves.append(line);
else moves.append(line, 0, line.size() - 1);
if (end) break;
}
bool legal = true;
for (const auto& m : moves) if (!tryMove(m)) { legal = false; break; }

if (t > 1) cout << endl;
cout << "Puzzle #" << t++ << ":" << endl;
if (legal) printGrid();
else cout << "This puzzle has no final configuration." << endl;
}
return 0;
}要点：
用map 模拟点的方向；
map<char, Point> DIRS = { { 'A',Point(-1, 0) },{ 'B',Point(1, 0) },{ 'L',Point(0, -1) },{ 'R',Point(0, 1) }, };使用 std::vector.count(char cmd) 来确定是否存在 字符 cmd，返回1和0，assert（）如果 返回0 就直接不执行下列语句。
assert(DIRS.count(cmd));使用std::string.rbegin() 获取string字符串的第一个字符，
bool end = *(line.rbegin()) == '0';