Floyd算法求最短路径

代码

// Floyd算法求最短路径
#include <cstdlib>
#include <string>
#include <iostream>
#include <fstream>
#include <vector>
#include <sstream>
#include <unordered_map>
#include <unordered_set>
#include <map>
#include <set>
#include <stdio.h>
#include <string.h>
#include <numeric>
#include <algorithm>
#include <functional>

using namespace std;
typedef long long ll;
const int MOD = 1e9 + 7;
typedef unsigned char uchar;

int dirs[8][2] = { -1, -1, -1, 0, -1, 1, 0, -1, 0, 1, 1, -1, 1, 0, 1, 1 };

#define MAX_DIST 1e9

// 无向图的Floyd算法
int main(int /*argc*/, char** /*argv*/)
{
    int N, M;
    // N为顶点数，M为边的个数
    scanf("%d %d", &N, &M);
    vector< vector<int> > nums( N+1, vector<int>(N+1, MAX_DIST) );
    int start, end, dist;
    // 输入M个边的顶点以及对应路径的距离
    for (int i = 0; i < M; ++i)
    {
        scanf("%d %d %d", &start, &end, &dist);
        nums[start][end] = dist;
        nums[end][start] = dist;
    }

    for (int i = 1; i <= N; ++i)
    {
        nums[i][i] = 0;
    }
    // 找到最短路径
    for (int w = 1; w <= N; ++w)
    {
        for (int i = 1; i <= N; ++i)
        {
            for (int j = i+1; j <= N; ++j)
            {
                if (nums[i][w] + nums[w][j] < nums[i][j])
                {
                    nums[i][j] = nums[i][w] + nums[w][j];
                    nums[j][i] = nums[i][j];
                }

            }
        }
    }
    printf("%d\n", nums[1][N]);

    system("pause");
    return 0;
}