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最新推荐文章于 2020-09-13 22:10:18 发布

unixcsir

最新推荐文章于 2020-09-13 22:10:18 发布

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分类专栏： NetWork Flow 文章标签： insert path sap

本文链接：https://blog.youkuaiyun.com/unixcsir/article/details/8001497

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First bs output under this title, and then built the diagram is very simple, it needs an overhaul

#include <cstdio>
#include <cstring>
#include <queue>
#include <algorithm>
#define DIR		4
#define MAXS	22
#define MAXN	805
#define MAXM	75000
#define INF		0x7fffffff
using namespace std;

struct Edge {
	int v, val, next;
}edge[MAXM];

char maze[MAXS][MAXS];
int row, col, e_cnt, used[MAXS][MAXS];
int head[MAXN], dis[MAXN], gap[MAXN], cur[MAXN], pre[MAXN];
int dir[][2] = { {1, 0}, {0, 1}, {-1, 0}, {0, -1} };

void insert_arc(int u, int v, int w)
{
	edge[e_cnt].v = v;	edge[e_cnt].val = w;
	edge[e_cnt].next = head[u];	head[u] = e_cnt ++;
	swap(u, v);
	edge[e_cnt].v = v;	edge[e_cnt].val = 0;
	edge[e_cnt].next = head[u];	head[u] = e_cnt ++;
}

void bfs(int src, int des)
{
	int u, v;
	queue<int> q;
	memset(dis, -1, sizeof(dis));
	memset(gap, 0, sizeof(gap));
	dis[des] = 0;	gap[0] = 1;
	q.push(des);

	while( !q.empty() ) {
		u = q.front(); q.pop();
		for(int i = head[u]; -1 != i; i = edge[i].next) {
			v = edge[i].v;
			if( edge[i].val || -1 != dis[v] )	continue;
			dis[v] = dis[u]+1;	gap[dis[v]] ++;
			q.push(v);
		}
	}
}

int i_sap(int source, int sink, int e_v)
{
	int u(source), v, min_dis, max_flow(0), path_flow(INF);
	bfs(source, sink);
	for(int i = 0; i <= e_v; i ++)
		cur[i] = head[i];

	pre[u] = u;
	while( dis[source] < e_v ) {
loop:
		for(int &i = cur[u]; -1 != i; i = edge[i].next) {
			v = edge[i].v;
			if( !edge[i].val || (dis[u] != dis[v]+1) )	continue;
			pre[v] = u;	path_flow = min(path_flow, edge[i].val);
			u = v;
			if( v == sink ) {
				for(u = pre[u]; v != source; v = u, u = pre[u]) {
					edge[cur[u]].val -= path_flow;	edge[cur[u]^1].val += path_flow;
				}
				max_flow += path_flow;	path_flow = INF;
			}
			goto loop;
		}
		min_dis = e_v;
		for(int i = head[u]; -1 != i; i = edge[i].next) {
			v = edge[i].v;
			if( edge[i].val && min_dis > dis[v] ) {
				min_dis = dis[v]; cur[u] = i;
			}
		}
		gap[dis[u]] --;
		if( !gap[dis[u]] )	break;
		dis[u] = min_dis+1;
		gap[ dis[u] ] ++;	u = pre[u];
	}
	//printf("max_flow = %d\n", max_flow);
	return max_flow;
}

void dfs(const int &index, int x, int y, int cur, int tar, int &flag)
{
	if( cur >= tar )	return;
	int tx, ty;
	if( ( !x || !y || (x == row-1) || (y == col-1) ) && (tar-cur>=1) ) {
		flag = 1;
	}

	used[x][y] = 1;
	for(int i = 0; i < DIR; i ++) {
		tx = dir[i][0]+x; ty = dir[i][1]+y;
		if( tx < 0 || ty < 0 || tx >= row || ty >= col ) {
			continue;
		}
		if( used[tx][ty] ) {
			continue;
		}
		if( maze[tx][ty] != '0' ) {
			insert_arc(tx*+colty+row*col, index, INF);
		}
		dfs(index, tx, ty, cur+1, tar, flag);
	}
	used[x][y] = 0;
}

int main(int argc, char const *argv[])
{
	//freopen("test.in", "r", stdin);
	int cnt(1), cas, jump, src, des, idx, d, flag;
	scanf("%d", &cas);
	while( cas-- ) {
		scanf("%d %d", &row, &jump);
		for(int i = 0; i < row; i ++) {
			scanf("%s", maze[i]);
		}
		col = strlen(maze[0]);
		src = row*col*2+1; des = src+1;
		e_cnt = 0;	memset(head, -1, sizeof(head));

		for(int i = 0; i < row; i ++) {
			for(int j = 0; j < col; j ++) {
				idx = i*col+j;	flag = 0;
				if( '0' == maze[i][j] )	continue;
				insert_arc(idx, idx+row*col, maze[i][j]-'0');
				memset(used, 0, sizeof(used));
				dfs(idx, i, j, 0, jump, flag);
				if( flag ) {
					insert_arc(idx+row*col, des, INF);
				}
			}
		}

		for(int i = 0; i < row; i ++)
			scanf("%s", maze[i]);

		int ans(0);
		for(int i = 0; i < row; i ++) {
			for(int j = 0; j < col; j ++) {
				if( 'L' == maze[i][j] ) {
					ans ++;
					insert_arc(src, i*col+j, 1);
				}
			}
		}

		ans -= i_sap(src, des, des+1);
        printf("Case #%d: ",cnt ++);
        if( ans == 0 ) printf("no lizard was left behind.\n");
        else if( ans == 1 ) printf("1 lizard was left behind.\n");
        else printf("%d lizards were left behind.\n",ans);
	}
	return 0;
}