POJ 2570 floyd 二进制

最新推荐文章于 2021-08-26 21:10:09 发布

原创最新推荐文章于 2021-08-26 21:10:09 发布 · 401 阅读

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本文介绍了一种改进的最短路算法，通过优化mp数组的更新方式，实现高效路径查找。通过实例演示算法的实现过程，并提供代码片段进行验证。

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将最短路条件改成mp[i][j] = mp[i][j] | (mp[i][k] & mp[k][j]);

#include <set>
#include <map>
#include <cmath>
#include <queue>
#include <stack>
#include <string>
#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;

typedef  long long LL;
const double PI = acos(-1.0);

template <class T> inline  T MAX(T a, T b){if (a > b) return a;return b;}
template <class T> inline  T MIN(T a, T b){if (a < b) return a;return b;}

const int N = 111;
const int M = 11111;
const LL MOD = 1000000007LL;
const int dir[4][2] = {1, 0, -1, 0, 0, -1, 0, 1};
const int INF = 0x3f3f3f3f;

int mp[222][222];



int main()
{
    int n;
    while (scanf("%d", &n) != EOF && n)
    {
        int i, j, k, u, v, bit;
        memset(mp, 0, sizeof(mp));
        char str[100];
        while (1)
        {
            scanf("%d%d", &u, &v);
            if (u == 0 && v == 0) break;
            scanf("%s", str);
            int l = strlen(str);
            bit = 0;
            for (j = 0; j < l; ++j)
            {
                bit |= (1 << (str[j] - 'a'));
            }
            mp[u][v] = bit;
        }
        for (k = 1; k <= n; ++k)
            for (i = 1; i <= n; ++i)
                for (j = 1; j <= n; ++j)
                {
                    mp[i][j] = mp[i][j] | (mp[i][k] & mp[k][j]);
                }
        while (1)
        {
            scanf("%d%d", &u, &v);
            if (u == 0 && v == 0) break;
            if (mp[u][v] == 0)
            {
                printf("-\n");
            }
            else
            {
                for (i = 0; i < 26; ++i)
                    if (mp[u][v] & (1 << i)) printf("%c",i + 'a');
                printf("\n");
            }
        }
        printf("\n");
    }
    return 0;
}