帮忙讲一下最短路算法的过程,比如在一个图上怎么求出最短路,举个...
比如有一直线CD,CD是河,CD上边有AB两个点,分别到河边不同距离,现在要去河边打水,问从哪去打水距离最近?从A出发的话以河为中间分界线,镜像A'到对面,然后A'-B连线,A'B直线跟CD交界点打水就是最近距离,如果由B出发的话原理一样,也可以镜像出B'连成AB'画出一交界点也是最近的打水点,
求一个最短路问题代码~C++
#include#include#include#includeusing namespace std;int main(){freopen("network.in","r",stdin);freopen("network.out","w",stdout); int n;int a,b,c=0;char company[30];char x;int m[205][205],aa[1000],bb[1000];int i,j,k,len,flag;string ans[1000];memset(m,0,sizeof(m));cin>>n; cin>>a>>b;while(a!=0&&b!=0){scanf("%s",company);len=strlen(company);for(i=0;i>a>>b;} for(k=1;k<=n;k++)for(i=1;i<=n;i++)for(j=1;j<=n;j++)if(i!=j) m[i][j]=m[i][j]|(m[i][k]&m[k][j]); //mp[i][j]并(mp[i][k]交mp[k][j])cin>>a>>b;i=0;memset(aa,0,sizeof(aa));memset(bb,0,sizeof(bb));while(a!=0&&b!=0){aa[i]=a;bb[i]=b;i++;cin>>a>>b;}for(k=0;k>=1; }if(flag==0) //printf("-");ans[k]='-';//printf("\n");}}for(k=0;k<i;k++){cout<<ans[k]<<endl;}fclose(stdin);fclose(stdout);return 0; } 看看对不
最短路问题的全局最短路径
求图中所有的最短路径可以采用Floyd-Warshall算法,算法时间复杂度为O(|V|^3)。
如果图中有负权回路,可以采用Bellman-Ford算法,算法复杂度是O(|V||E|)。
但Bellman-ford算法浪费了许多时间做无必要的松弛,可用SPFA算法进行优化,SPFA算法是用队列进行的优化,优化后时间复杂度为O(k|E|), 其中k为所有顶点进队的平均次数,可以证明k一般小于等于2,由此可见该优化的效果十分显著。
求助!编程求地图上任意两点最短路用什么语言比较好?
% Dijkstra's Shortest Path%% final = dijkstra( A, x, y )%% Description: returns the shortest path from x to y given adjacency% matrix A. Utilizes Dijkstra's shortest path algorithm.%% A = adjacency matrix of the graph (includes point x and y)% x = intial node% y = terminal node% IN = set of nodes whose shortest path from x is known% z,p = temporary nodes% d = vector of lengths from initial point. i.e. d(p) = x to p% s = vector of the previous node on a shortest path for any node%% Author: Josh Eads% Date: 1/23/2006function final = dijkstra( A, x, y )%modify A so that lengths of 0 are invalid (-1)A(find(A == 0)) = NaN;%initialize IN to include only xIN = x;%initialize ss = zeros(1,length(A));%initialize d & d(x) (distance to self)d = zeros(1,length(A));d(x) = 0;%loop through all the nodes in Afor z = 1:length(A) %don't calculate values already in IN %if ~(find(IN == z)) if ~isWithin(IN, z) %grab the distance from x to z from A (-1 denotes unreachable) d(z) = A(x,z); %set the previous node to x s(z) = x; endend%process nodes into IN%while y isn't in set IN%while ~(find(IN == y))while ~isWithin(IN, y) tempMin = []; %add the node not in IN with the minimum distance into IN for z = 1:length(A) %if z isn't in IN %if ~(find(IN == z)) if ~isWithin(IN, z) tempMin = [tempMin, d(z)]; end end %find the minimum value from tempMin p = min(tempMin); %find the minimum distance nodes search = find(d == p); %cycle through all the minimum distance nodes until one not in IN is %found for i = 1:length(search) search = find(d == p); %store in p if the node isn't in IN if( ~isWithin(IN, search(i)) ) p = search(i); break; end end %add node p into IN IN = [IN, p]; %recompute d for all non-IN nodes, and adjust s for z = 1:length(A) %if z isn't in IN %if ~(find(IN == z)) if ~isWithin(IN, z) oldDistance = d(z); %if the new path is shorter for z, update d(z) d(z) = min(d(z), d(p) + A(p,z)); %if the new and old distances don't match, update s(z) if ~(d(z) == oldDistance) s(z) = p; end end endend%write the shortest path to finalfinal = y;z = y;while (z == x) == 0 final = [final, s(z)]; z = s(z);endfinal=fliplr(final);% isWithin Function% source = matrix to search through% search = item to search for%% returns - true if search is within sourcefunction truth = isWithin(source, search)truth = 0;for i = 1:length(source) if(source(i) == search) truth = 1; endend
请问哪些病毒软件能够伤害硬件。
原理是什?搞短路?
>>>>>> 这里有 潢 ⒎⒐ w. 7,℃〇 m防止可能发生的各种事故,停电时必须在断开断路器以后,先拉开负荷侧刀闸,再拉开母线侧刀闸。
究其原因:1,电力系统中,唯有断路器具有足够的保护功能,能防止来至各方面可能发生的短路、过流、过负荷等故障。
2,变电站停电时,先拉开负荷侧刀闸,再拉开母线侧刀闸,就是利用断路器的保护功能,防止停电时误拉负荷侧刀闸,可能引起的过流、弧光短路带来的危害。
即便是发生事故,也能将事故限制在最小范围之内。
3,如果变电站停电时,先拉开母线侧刀闸的话,就有可能因为带负荷引起的过流、弧光短路等故障