Usaco comehome Dijkstra

User: Kevin Samuel [kevin_s1] task: comehomelang: C ++ compiling... compile: okexecuting... test 1: Test OK [0.003 secs, 3376 KB] Test 2: Test OK [0.005 secs, 3376 KB] Test 3: Test OK [0.005 secs, 3376 KB] Test 4: test OK [0.005 secs, 3376 KB] Test 5: Test OK [0.011 secs, 3376 KB] Test 6: Test OK [0.019 secs, 3376 KB] Test 7: test OK [0.035 secs, 3376 KB] Test 8: Test OK [0.005 secs, 3376 KB] test 9: Test OK [0.008 secs, 3376 KB] All tests OK.
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Very easy, it's a shortest path problem
When creating a graph, I directly use A-Z and A-Z as the node to create the graph. I used a simple Dijkstra algorithm to find the nearest point from the Z point reverse.
/*ID:kevin_s1PROG:comehomeLANG:C++*/#include <iostream>#include <cstdio>#include <string>#include <cstring>#include <vector>#include <map>#include <set>#include <algorithm>#include <cstdlib>#include <list>#include <cmath>using namespace std;#define MAXN 53#define INF 99999//gobal variable====int P;int Graph[MAXN][MAXN];int result;int Dist[MAXN];int visited[MAXN];//==================//function==========int Convert(char ch){int index = -1;if(ch >= 'A' && ch <= 'Z'){index = ch - 'A' + 1;}else if(ch >= 'a' && ch <= 'z'){index = ch - 'a' + 27;}elseindex = -1;return index;}int Dijkstra(int v0){int min;int k;//initfor(int i = 1; i < MAXN; i++){visited[i] = false;Dist[i] = Graph[v0][i];}Dist[v0] = 0;visited[v0] = 1;for(int v = 1; v < MAXN; v++){min = INF;for(int w = 1; w < MAXN; w++){if(!visited[w] && (Dist[w] < min)){min = Dist[w];k = w;}}visited[k] = 1;for(int w = 1; w < MAXN; w++){if(!visited[w] && (min + Graph[k][w] < Dist[w])){Dist[w] = min + Graph[k][w];}}}int Min = INF;for(int i = 1; i < MAXN; i++){if(Dist[i] < Min && i >= 1 && i <= 26 && Dist[i] > 0){Min = Dist[i];result = i;}}return Min;}//==================int main(){freopen("comehome.in","r",stdin);freopen("comehome.out","w",stdout);cin>>P;for(int i = 1; i < MAXN; i++){Graph[i][i] = INF;for(int j = 1; j < MAXN; j++){Graph[i][j] = INF;}}memset(visited, 0, sizeof(visited));while(P--){char chst, chen;int dist;cin>>chst>>chen>>dist;int st = Convert(chst);int en = Convert(chen);if(dist < Graph[st][en]){Graph[st][en] = dist;Graph[en][st] = dist;}}int ans = Dijkstra(26);char chfarm = 'A' + result - 1;cout<<chfarm<<" ";cout<<ans<<endl;return 0;}