【nwpu暑假集训搜索专题】（一）
表示我都没有跟着群巨暑假集训做题的节奏走，但是由于搜索太弱，所以就做了几道搜索题。
POJ 3278
#include <iostream>
#include <string>
#include <cstdio>
#include <cstring>
#include <stdlib.h>
using namespace std;
int n, k, maxn = 100001;
int a[100100];
int q[100100];
int bfs()
{
memset(a, 0, sizeof(a));
a[n] = 1;
int l = 0, r = 1;
q[0] = n;
while (l < r)
{
int x = q[l++];
if (!a[x - 1] && (x - 1 >= 0))
{
a[x - 1] = a[x] + 1;
q[r++] = x - 1;
if (x - 1 == k) return a[x] + 1;
}
if (!a[x + 1] && (x + 1 < maxn))
{
a[x + 1] = a[x] + 1;
q[r++] = x + 1;
if (x + 1 == k) return a[x] + 1;
}
if (!a[x * 2] && (x * 2 < maxn))
{
a[x * 2] = a[x] + 1;
q[r++] = x * 2;
if (x * 2 == k) return a[x] + 1;
}
}
}
int main()
{
while (scanf("%d%d", &n, &k) != EOF)
{
if (n == k) printf("0\n");
else printf("%d\n", bfs() - 1);
}
return 0;
}
POJ 1979
数联通块数目
#include<iostream>
#include<cstring>
#include<cstdio>
using namespace std;
int n, m, sx, sy;
char a[200][200];
void init()
{
memset(a, 0, sizeof(a));
for(int i = 1;i <= n; i++)
for(int j = 1; j <= m; j++)
{
cin >> a[i][j];
if (a[i][j] == '@')
{
sx = i;
sy = j;
}
if ((a[i][j] == '.') || (a[i][j] == '@'))
a[i][j] = 1;
else a[i][j] = 0;
}
}
long dfs(int i,int j)
{
long k = 1;
a[i][j] = 0;
if(a[i - 1][j] > 0) k += dfs(i - 1, j);
if(a[i + 1][j] > 0) k += dfs(i + 1, j);
if(a[i][j - 1] > 0) k += dfs(i, j - 1);
if(a[i][j + 1] > 0) k += dfs(i, j + 1);
return k;
}
int main()
{
cin >> m >> n;
while ((m != 0) && (n != 0))
{
init();
cout << dfs(sx, sy) << endl;
cin >> m >> n;
}
return 0;
}
骑士游历问题（写得好丑好丑哦）
#include <iostream> #include <string> #include <cstdio> #include <cstring> #include <stdlib.h> using namespace std; int v[400][400]; int qx[200000], qy[200000]; int t, n = 8, sx, tx, sy, ty; bool can (int x, int y) { if (x < 0) return false; if (y < 0) return false; if (x >= n) return false; if (y >= n) return false; if (v[x][y] != 0) return false; return true; } int bfs() { memset(v, 0, sizeof(v)); v[sx][sy] = 1; int l = 0, r = 1; qx[0] = sx; qy[0] = sy; while (l < r) { int x = qx[l], y = qy[l++]; if (x == tx && y == ty) return v[x][y]; if (can(x - 1, y - 2)) { v[x-1][y-2] = v[x][y] + 1; qx[r] = x-1; qy[r++] = y-2; } if (can(x - 2, y - 1)) { v[x-2][y-1] = v[x][y] + 1; qx[r] = x-2; qy[r++] = y-1; } if (can(x - 2, y + 1)) { v[x-2][y+1] = v[x][y] + 1; qx[r] = x-2; qy[r++] = y+1; } if (can(x - 1, y + 2)) { v[x-1][y+2] = v[x][y] + 1; qx[r] = x-1; qy[r++] = y+2; } if (can(x + 1, y - 2)) { v[x+1][y-2] = v[x][y] + 1; qx[r] = x+1; qy[r++] = y-2; } if (can(x + 2, y - 1)) { v[x+2][y-1] = v[x][y] + 1; qx[r] = x+2; qy[r++] = y-1; } if (can(x + 2, y + 1)) { v[x+2][y+1] = v[x][y] + 1; qx[r] = x+2; qy[r++] = y+1; } if (can(x + 1, y + 2)) { v[x+1][y+2] = v[x][y] + 1; qx[r] = x+1; qy[r++] = y+2; } } } int main() { char c1, c2; int y1, y2; while (scanf(" %c%d %c%d", &c1, &y1, &c2, &y2) != EOF) { sx = c1 - 'a'; sy = y1 - 1; tx = c2 - 'a'; ty = y2 - 1; //cout << sx<< sy << tx << ty<< endl; printf("To get from %c%d to %c%d takes %d knight moves.\n",c1, y1, c2, y2, bfs() - 1); } return 0; }
POJ 1915
继续骑士游历
#include <iostream> #include <string> #include <cstdio> #include <cstring> #include <stdlib.h> using namespace std; int v[400][400]; int qx[200000], qy[200000]; int t, n, sx, tx, sy, ty; bool can (int x, int y) { if (x < 0) return false; if (y < 0) return false; if (x >= n) return false; if (y >= n) return false; if (v[x][y] != 0) return false; return true; } int bfs() { memset(v, 0, sizeof(v)); v[sx][sy] = 1; int l = 0, r = 1; qx[0] = sx; qy[0] = sy; while (l < r) { int x = qx[l], y = qy[l++]; if (x == tx && y == ty) return v[x][y]; if (can(x - 1, y - 2)) { v[x-1][y-2] = v[x][y] + 1; qx[r] = x-1; qy[r++] = y-2; } if (can(x - 2, y - 1)) { v[x-2][y-1] = v[x][y] + 1; qx[r] = x-2; qy[r++] = y-1; } if (can(x - 2, y + 1)) { v[x-2][y+1] = v[x][y] + 1; qx[r] = x-2; qy[r++] = y+1; } if (can(x - 1, y + 2)) { v[x-1][y+2] = v[x][y] + 1; qx[r] = x-1; qy[r++] = y+2; } if (can(x + 1, y - 2)) { v[x+1][y-2] = v[x][y] + 1; qx[r] = x+1; qy[r++] = y-2; } if (can(x + 2, y - 1)) { v[x+2][y-1] = v[x][y] + 1; qx[r] = x+2; qy[r++] = y-1; } if (can(x + 2, y + 1)) { v[x+2][y+1] = v[x][y] + 1; qx[r] = x+2; qy[r++] = y+1; } if (can(x + 1, y + 2)) { v[x+1][y+2] = v[x][y] + 1; qx[r] = x+1; qy[r++] = y+2; } } } int main() { scanf("%d", &t); while (t--) { scanf("%d", &n); scanf("%d%d", &sx, &sy); scanf("%d%d", &tx, &ty); printf("%d\n", bfs() - 1); } return 0; }
POJ 3984
走迷宫搜方案
#include <iostream>
#include <string>
#include <cstdio>
#include <cstring>
#include <stdlib.h>
using namespace std;
int a[5][5];
int v[5][5];
int qx[40], qy[40];
bool can (int x, int y)
{
if (x < 0) return false;
if (y < 0) return false;
if (x >= 5) return false;
if (y >= 5) return false;
if (a[x][y] == 1) return false;
if (v[x][y] != 0) return false;
return true;
}
void bfs()
{
memset(v, 0, sizeof(v));
v[0][0] = 1;
int l = 0, r = 1;
qx[0] = 0;
qy[0] = 0;
while (l < r)
{
int x = qx[l], y = qy[l++];
if (can(x - 1, y))
{
v[x - 1][y] = v[x][y] + 1;
qx[r] = x - 1;
qy[r++] = y;
if (x - 1 == 4 && y == 4) return;
}
if (can(x + 1, y))
{
v[x + 1][y] = v[x][y] + 1;
qx[r] = x + 1;
qy[r++] = y;
if (x + 1 == 4 && y ==4) return;
}
if (can(x, y - 1))
{
v[x][y - 1] = v[x][y] + 1;
qx[r] = x;
qy[r++] = y - 1;
if (x == 4 && y - 1 == 4) return;
}
if (can(x, y + 1))
{
v[x][y + 1] = v[x][y] + 1;
qx[r] = x;
qy[r++] = y + 1;
if (x == 4 && y + 1 == 4) return;
}
}
}
void dfs(int x, int y)
{
if (x != 0 || y != 0)
{
if (x > 0 && v[x - 1][y] == v[x][y] - 1) dfs(x - 1, y);
if (x < 4 && v[x + 1][y] == v[x][y] - 1) dfs(x + 1, y);
if (y > 0 && v[x][y - 1] == v[x][y] - 1) dfs(x, y - 1);
if (y < 4 && v[x][y + 1] == v[x][y] - 1) dfs(x, y + 1);
}
printf("(%d, %d)\n", x, y);
}
int main()
{
for (int i = 0; i < 5; i++)
for (int j = 0; j < 5; j++)
scanf("%d", &a[i][j]);
bfs();
// for (int i = 0; i < 5; i++)
// {
// for (int j = 0; j < 5; j++)
// cout << v[i][j] << ' ';
// cout << endl;
// }
dfs(4,4);
return 0;
}