题解

#include <iostream>
#include <cstdio>
#include <vector>
#include <queue>
using namespace std;
struct node1{
	int opr;//1:倒入 2:清空 3:把水倒入另一个桶
	bool tmp;
};
struct node{
	vector <node1> v;
	int x = 0, y = 0, step = 0;
};
bool vis[105][105];
int n, m, k;
node bfs(){
	node xxxxx;
	queue <node> q;
	q.push(xxxxx);
	while(!q.empty()){
		node head = q.front();
		q.pop();
		if(head.x == k || head.y == k) return head;
        //开始痛苦
		node tmp = head;
		tmp.x = n;//FILL1
		if(!vis[tmp.x][tmp.y]){
			vis[tmp.x][tmp.y] = 1;
			tmp.step++, tmp.v.push_back({1, 0});
			q.push(tmp);
		}
		tmp = head;
		tmp.y = m;//FILL2
		if(!vis[tmp.x][tmp.y]){
			vis[tmp.x][tmp.y] = 1;
			tmp.step++, tmp.v.push_back({1, 1});
			q.push(tmp);
		}
		tmp = head;
		tmp.x = 0;//DROP1
		if(!vis[tmp.x][tmp.y]){
			vis[tmp.x][tmp.y] = 1;
			tmp.step++, tmp.v.push_back({2, 0});
			q.push(tmp);
		}
		tmp = head;
		tmp.y = 0;//DROP2
		if(!vis[tmp.x][tmp.y]){
			vis[tmp.x][tmp.y] = 1;
			tmp.step++, tmp.v.push_back({2, 1});
			q.push(tmp);
		}
		tmp = head;
		if(tmp.x + tmp.y <= n){//POUR12
			tmp.x += tmp.y, tmp.y = 0;
		}else{
			tmp.y -= (n - tmp.x), tmp.x = n;
		}
		if(!vis[tmp.x][tmp.y]){
			vis[tmp.x][tmp.y] = 1;
			tmp.step++, tmp.v.push_back({3, 0});
			q.push(tmp);
		}
		tmp = head;
		if(tmp.x + tmp.y <= m){//POUR21
			tmp.y += tmp.x, tmp.x = 0;
		}else{
			tmp.x -= (m - tmp.y), tmp.y = m;
		}
		if(!vis[tmp.x][tmp.y]){
			vis[tmp.x][tmp.y] = 1;
			tmp.step++, tmp.v.push_back({3, 1});
			q.push(tmp);
		}
	}
	return xxxxx;
}
int main(){
	cin >> n >> m >> k;
	node ans = bfs();
	if(ans.step == 0){
		cout << "impossible";
		return 0;
	}
	cout << ans.step << endl;
	for(int i = 0; i < ans.v.size(); i++){
		if(ans.v[i].opr == 1){
			printf("FILL(%d)\n", ans.v[i].tmp + 1);
		}
		else if(ans.v[i].opr == 2){
			printf("DROP(%d)\n", ans.v[i].tmp + 1);
		}else{
			printf("POUR(%d,%d)\n", 2 - ans.v[i].tmp, ans.v[i].tmp + 1);
		}
	}

	return 0;
}