UVA439

题目意思就是在一个8　×　8　的棋盘上，ａ代表１，ｂ代表２这样。。然后从一个位置移动到另一个位置，最少要几步；国际象棋中的骑士，和象棋中的马是一样的，走日字；；用ｂｆｓ（）搜一边。。#include<stdio.h>#include<queue>#include<iostream>#include<string>using namespace std;const int N = 20;int bx,by;int ex,ey;bool cheer[N][N];int pos[N * N];bool vis[N][N];struct squ {int x;int y;int dis;}p1,p2;int cx[8] = {-2,-2,2,2,-1,1,-1,1};int cy[8] = {-1,1,-1,1,2,2,-2,-2};queue<squ> q;bool ok;int res;void init() {for (int i = 0 ; i < N ;i++) {for (int  j = 0; j < N; j++) {cheer[i][j] = false;vis[i][j] = false;}}for (int i = 0 ; i < N * N ; i++) {pos[i] = i - 96;}while(!q.empty())q.pop();ok = false;res = 0;}bool canbe(int x,int y) {if(x < 1 || y < 1 || x > 8 || y > 8 ||vis[x][y] == true)return false;return true;}void bfs() {p1.x = bx;p1.y = by;p1.dis = 0;q.push(p1);vis[bx][by] = true;while(!q.empty()) {p1 = q.front();q.pop();int x = p1.x;int y = p1.y;int s = p1.dis;for (int i = 0 ; i < 8 ;i++) {int x1 = x + cx[i];int y1 = y + cy[i];if (canbe(x1,y1)) {if ( x1 == ex && y1 == ey) {ok = true;res = s + 1;break;}vis[x1][y1] = true;p2.x = x1;p2.y = y1;p2.dis = s + 1;q.push(p2);}}if (ok == true)break;}}int main () {string str;while (getline (cin ,str)) {init();bx = pos[str[0]];by = str[1] - 48;ex = pos[str[3]];ey = str[4] - 48;bfs();cout <<"To get from " << str[0] << str[1] <<" to "<<str[3] <<str[4] << " takes "<<res<<" knight moves." <<endl;}}