POJ 1128 Frame Stacking（拓扑排序）

来源：互联网发布：阿里云大数据平台 sql 编辑：程序博客网时间：2024/05/29 16:04

本题需要一些构图上的小优化，构图之后博主我选择使用DFS来进行拓扑排序的操作，详情见代码

#include<cstdio>#include<cstring>#include<algorithm>#include<cmath>#include<iostream>#include<cstdlib>#include<string>#include<cassert>#include<set>#include<vector>#include<stack>#include<queue>#define clean(n,m) memset(n,m,sizeof(n))using namespace std;#define maxn 32#define maxm 28char map[maxn][maxm], ans[maxm];int m, n, in[maxn], total;bool edge[maxn][maxm];struct Node{    int x, y;}lt[maxm],rb[maxm];void getMap(){    clean(edge, false);    clean(in, -1);    clean(lt, 0x3f);    clean(rb, -1);    for (int i = total = 0;i < n;i++)    {        for (int j = 0;j < m;j++)        {            if (map[i][j] == '.')                continue;            int t = map[i][j] - 'A';            if (in[t] == -1)            {                in[t] = 0;                total++;            }            if (i < lt[t].x)                lt[t].x = i;            if (i > rb[t].x)                rb[t].x = i;            if (j < lt[t].y)                lt[t].y = j;            if (j > rb[t].y)                rb[t].y = j;        }    }    for (int i = 0;i < maxn;i++)    {        if (in[i] == -1)            continue;        for (int x = lt[i].x;x <= rb[i].x;x++)        {            for (int y = lt[i].y;y <= rb[i].y;y++)            {                if (x > lt[i].x&&y > lt[i].y&&x < rb[i].x&&y < rb[i].y)                    continue;                int t = map[x][y] - 'A';                if (t != i&&!edge[i][t])                {                    edge[i][t] = true;                    in[t]++;                }            }        }    }}void dfs(int id){    if (id == total)    {        ans[id] = '\0';        cout << ans << endl;        return;    }    for (int i = 0;i < maxn;i++)    {        if (in[i] == 0)        {            ans[id] = 'A' + i;            in[i] = -1;            for (int j = 0;j < maxn;j++)            {                if (edge[i][j])                    in[j]--;            }            dfs(id + 1);            in[i] = 0;            for (int j = 0;j < maxn;j++)            {                if (edge[i][j])                    in[j]++;            }        }    }}int main(){    while (cin >> n >> m)    {        for (int i = 0;i < n;i++)            cin >> map[i];        getMap();        dfs(0);    }    return 0;}

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