(step4.2.5)hdu 1495(非常可乐—

(step4.2.5)hdu 1495(非常可乐——BFS)

快来打我* 2021-12-13 14:47 277阅读 0赞

题目大意：输入三个整数 a,b,c. a : 可乐瓶的容量，b: 甲杯的容量，c: 乙杯的容量。问能否用这三个被来实现饮料的平分？？？如果可以输出倒饮料的次数,

否则输出NO

解题思路:BFS

1）本题的考点其实在于将标记数组由二维数组变为三维数组。遍历状态由使用for()循环变为手动枚举，一个一个的if()

代码如下:

/*
 * 1495_2.cpp
 *
 *  Created on: 2013年8月16日
 *      Author: Administrator
 */
#include <iostream>
#include <queue>
using namespace std;
const int maxn = 102;
bool visited[maxn][maxn][maxn];
int a, b, c;
struct State {
    int a;
    int b;
    int c;
    int v;
};
bool checkState(State st) {
    if (!visited[st.a][st.b][st.c]) {
        return true;
    }
    return false;
}
void bfs() {
    queue<State> q;
    State st, now, next;
    st.a = a;
    st.b = 0;
    st.c = 0;
    st.v = 0;
    q.push(st);
    memset(visited,0,sizeof(visited) );
    visited[st.a][st.b][st.c] = 1;
    while (!q.empty()) {
        now = q.front();
        //有2个等于a/2就结束
        if ((now.a == a / 2 && now.b == a / 2)
                || (now.a == a / 2 && now.c == a / 2)
                || (now.c == a / 2 && now.b == a / 2)) {
            printf("%d\n", now.v);
            return ;
        }
        /**
         * 若a杯中的饮料的体积不为0,
         * 则枚举出将a杯中的饮料倒到其他杯中....
         */
        if (now.a != 0) {
            /**
             * 关键举得理解:now.a > b - now.b
             * now.a : now状态下a杯中的饮料的体积
             * b : b杯的体积
             * now.b :now状态下b杯中的饮料的体积
             *
             */
            if (now.a > b - now.b) {//now.a > b - now.b。且倒不完
                next.a = now.a - (b - now.b);
                next.b = b;
                next.c = now.c;
                next.v = now.v + 1;
            } else {//倒完了
                next.a = 0;
                next.b = now.b + now.a;
                next.c = now.c;
                next.v = now.v + 1;
            }
            if (checkState(next)) {
                q.push(next);
                visited[next.a][next.b][next.c] = 1;
            }
            if (now.a > c - now.c) {
                next.a = now.a - (c - now.c);
                next.b = now.b;
                next.c = c;
                next.v = now.v + 1;
            } else {
                next.a = 0;
                next.b = now.b;
                next.c = now.c + now.a;
                next.v = now.v + 1;
            }
            if (checkState(next)) {
                q.push(next);
                visited[next.a][next.b][next.c] = 1;
            }
        }
        if (now.b != 0) {
            if (now.b > a - now.a) {
                next.a = a;
                next.b = now.b - (a - now.a);
                next.c = now.c;
                next.v = now.v + 1;
            } else {
                next.a = now.a + now.b;
                next.b = 0;
                next.c = now.c;
                next.v = now.v + 1;
            }
            if (checkState(next)) {
                q.push(next);
                visited[next.a][next.b][next.c] = 1;
            }
            if (now.b > c - now.c) {
                next.a = now.a ;
                next.b = now.b - (c - now.c);
                next.c = c;
                next.v = now.v + 1;
            } else {
                next.a = now.a;
                next.b = 0;
                next.c = now.c + now.b;
                next.v = now.v + 1;
            }
            if (checkState(next)) {
                q.push(next);
                visited[next.a][next.b][next.c] = 1;
            }
        }
        if (now.c != 0) {
            if (now.c > b - now.b) {
                next.a = now.a ;
                next.b = b;
                next.c = now.c - (b - now.b);
                next.v = now.v + 1;
            } else {
                next.a = now.a;
                next.b = now.b + now.c;
                next.c = 0;
                next.v = now.v + 1;
            }
            if (checkState(next)) {
                q.push(next);
                visited[next.a][next.b][next.c] = 1;
            }
            if (now.c > a - now.a) {
                next.a = a;
                next.b = now.b;
                next.c = now.c - (a - now.a);
                next.v = now.v + 1;
            } else {
                next.a = now.a + now.c;
                next.b = now.b;
                next.c = 0;
                next.v = now.v + 1;
            }
            if (checkState(next)) {
                q.push(next);
                visited[next.a][next.b][next.c] = 1;
            }
        }
        q.pop();
    }
    printf("NO\n");
}
int main() {
    while(scanf("%d%d%d",&a,&b,&c)!=EOF,a+b+c){
        if(a%2 == 1){
            printf("NO\n");
        }else{
            bfs();
        }
    }
}