【搜索】 FZU 2188 过河I

bfs搜索，x，y和船停的地方。

#include <iostream>
#include <queue>
#include <stack>
#include <map>
#include <set>
#include <bitset>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <climits>
#include <cstdlib>
#include <cmath>
#include <time.h>
#define maxn 50005
#define maxm 300005
#define eps 1e-3
#define mod 9999677
#define INF 0x3f3f3f3f
#define PI (acos(-1.0))
#define lowbit(x) (x&(-x))
#define mp make_pair
#define ls o<<1
#define rs o<<1 | 1
#define lson o<<1, L, mid 
#define rson o<<1 | 1, mid+1, R
#define pii pair<int, int>
#pragma comment(linker, "/STACK:16777216")
typedef long long LL;
typedef unsigned long long ULL;
using namespace std;
LL qpow(LL a, LL b){LL res=1,base=a;while(b){if(b%2)res=res*base;base=base*base;b/=2;}return res;}
LL powmod(LL a, LL b){LL res=1,base=a;while(b){if(b%2)res=res*base%mod;base=base*base%mod;b/=2;}return res;}
//head

struct node
{
	int x, y, t, u;
	node() {}
	node(int x, int y, int t, int u) : x(x), y(y), t(t), u(u) {}
};

queue<node> q;
int vis[2][205][205];
int n, nx, ny;

void bfs()
{
	int ans = -1;
	memset(vis, 0,  sizeof vis);
	vis[0][nx][ny] = true;
	while(!q.empty()) {
		int x = q.front().x, y = q.front().y;
		int t = q.front().t, u = q.front().u;
		q.pop();
	//	printf("AAA %d %d %d\n", x, y ,u);
		int xx = nx - x, yy = ny - y;
		if(x == 0 && y == 0) {
			ans = t;
			break;
		}
		if(u == 0) {
			for(int i = 0; i <= n && i <= x; i++)
				for(int j = 0; i + j <= n && j <= y; j++) {
					if(i == 0 && j == 0) continue;
					if(i && j > i) break;
					if(x - i && y - j > x - i) continue;
					if(xx + i && (yy + j) > xx + i) continue;
					if(!vis[1][x-i][y-j]) vis[1][x-i][y-j] = true, q.push(node(x - i, y - j, t+1, 1));
				}
		}
		else {
			for(int i = 0; i <= n && i <= xx; i++)
				for(int j = 0; i + j <= n && j <= yy; j++) {
					if(i == 0 && j == 0) continue;
					if(i && j > i) break;
					if(xx - i && yy - j > xx - i) continue;
					if(x + i && (y + j) > x + i) continue;
					if(!vis[0][x+i][y+j]) vis[0][x+i][y+j] = true, q.push(node(x + i, y + j, t+1, 0));
				}
		}
	}
	printf("%d\n", ans);
}

void work()
{
	if(nx && nx < ny) {
		printf("-1\n");
		return;
	}
	while(!q.empty()) q.pop();
	q.push(node(nx, ny, 0, 0));
	bfs();
}

int main()
{
	while(scanf("%d%d%d", &nx, &ny, &n)!=EOF) {
		work();
	}

	
	return 0;
}