Shortest Path
Time Limit: 4000/2000 MS (Java/Others) Memory Limit: 131072/131072 K (Java/Others)
Total Submission(s): 627 Accepted Submission(s): 204
You are given the graph and several queries about the shortest path between some pairs of vertices.
The first line contains two integer n and m (1≤n,m≤105) -- the number of vertices and the number of queries. The next line contains 6 integers a1,b1,a2,b2,a3,b3 (1≤a1,a2,a3,b1,b2,b3≤n), separated by a space, denoting the new added three edges are (a1,b1), (a2,b2), (a3,b3).
In the next m lines, each contains two integers si and ti (1≤si,ti≤n), denoting a query.
The sum of values of m in all test cases doesn't exceed 106.
如果想做出这道题, 重要的是思路和知识的熟练掌握, Floyd模板并不难, 但怎么将它巧妙的用到了题中是值得思考的问题,还是自己掌握的不熟练, 一看别人的就懂, 但让自己写却毫无头绪
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <map>
#include <cmath>
#include <iostream> using namespace std; #define MOD (1000000000+7) int main()
{
int T;
scanf("%d", &T); while(T--)
{
int n, m, i, j, k, l, r, u, v, a[10];
int dp[10][10];
long long res=0, len; scanf("%d%d", &n, &m); for(i=1; i<=6; i++)
scanf("%d", &a[i]); for(i=1; i<=6; i++) ///相当于对dp初始化
for(j=1; j<=6; j++)
dp[i][j] = abs(a[i]-a[j]); if(a[1]!=a[2]) dp[1][2] = dp[2][1] = 1; ///如果两点不相等的话就让两点的距离为1
if(a[3]!=a[4]) dp[3][4] = dp[4][3] = 1;
if(a[5]!=a[6]) dp[5][6] = dp[6][5] = 1; for(k=1; k<=6; k++)
for(i=1; i<=6; i++)
for(j=1; j<=6; j++)
dp[i][j] = min(dp[i][j], dp[i][k]+dp[k][j]); for(i=1; i<=m; i++)
{
scanf("%d%d", &l, &r);
len = abs(l-r); for(u=1; u<=6; u++)
for(v=1; v<=6; v++)
len = min(len, (long long)(abs(a[u]-l)+dp[u][v]+abs(a[v]-r))); res = (res+len*i)%MOD;
} printf("%I64d\n", res); }
return 0;
}