今天上午写代码的时候有点困,结果这道题改了好久(赋值等号两边写反了竟然
所以还是要早点睡觉 @-@
我用的弗洛伊德最短路径算法,改了半天测试点4过不去,代码如下:
#include<iostream>
#include<vector>
#include<string>
using namespace std;
#define inf 1e5
vector<vector<int>>d;
int main() {
int N, M, K, Ds;
cin >> N >> M >> K >> Ds;
d.resize(N + M + 1);
for (int i = 1; i <= N + M; i++)
d[i].resize(1 + N + M, inf);
for (int i = 1; i <= N + M; i++)
d[i][i] = 0;
for (int i = 1; i <= K; i++) {
string in[2]; int distance;
int index[2];
cin >> in[0] >> in[1] >> distance;
for (int j = 0; j < 2; j++) {
if (in[j][0] == 'G') {
in[j].erase(in[j].begin());
index[j] = N + stoi(in[j]);
}
else
index[j] = stoi(in[j]);
}
d[index[0]][index[1]] = distance;
d[index[1]][index[0]] = distance;
}
for (int i = 1; i <= N + M; i++) {
for (int j = 1; j <= N + M; j++) {
if (i == j) continue;
for (int k = 1; k <= N + M; k++) {
if (d[i][k] + d[k][j] < d[i][j]) {
d[i][j] = d[i][k] + d[k][j];
}
}
}
}
int min = 0; int index = -1; float ave = 0;
for (int i = N + 1; i <= N + M ; i++) {
int temp = 1e9; int s = 0; int flag = 1;
for (int j = 1; j <= N; j++) {
if (d[i][j] > Ds) {
flag = 0; break;
}
s += d[i][j];
if (d[i][j] < temp) temp = d[i][j];
}
if (flag == 0) continue;
if (temp > min) {
min = temp;
index = i;
ave = (float)s / N;
}
else if (temp == min) {
if ((float)s / N < ave) {
index = i;
ave = (float)s / N;
}
}
}
if (index == -1) cout << "No Solution";
else {
printf("G%d\n%.1f %.1f", index - N, (float)min, ave);
}
return 0;
}
没办法,还是用迪杰拉斯算法吧(本来想偷个懒的哈哈
思路参考:PAT甲级真题 1072 Gas Station (30分) C++实现(Dijkstra算法,测试点4四舍五入的坑)_zhang35的博客-CSDN博客
改了好久啊啊啊啊啊啊,终于AC了(哭
#include<iostream>
#include<vector>
#include<string>
using namespace std;
#define inf 1e5
vector<vector<int>>d;
vector<int>s;
vector<vector<int>>result;
int main() {
int N, M, K, Ds;
cin >> N >> M >> K >> Ds;
//init
d.resize(N + M + 1);
s.resize(N + M + 1);
result.resize(M + 1);
for (int i = 1; i <= N + M; i++)
d[i].resize(1 + N + M, inf);
for (int i = 1; i <= M; i++) {
result[i].resize(1 + N + M, inf);
result[i][i+N] = 0;
}
for (int i = 1; i <= N + M; i++)
d[i][i] = 0;
//input info
for (int i = 1; i <= K; i++) {
string in[2]; int distance;
int index[2];
cin >> in[0] >> in[1] >> distance;
for (int j = 0; j < 2; j++) {
if (in[j][0] == 'G') {
in[j].erase(in[j].begin());
index[j] = N + stoi(in[j]);
}
else
index[j] = stoi(in[j]);
}
d[index[0]][index[1]] = distance;
d[index[1]][index[0]] = distance;
}
//dij
for (int i = 1; i <= M; i++) {
fill(s.begin(), s.begin() + N + M+1, 0);
for (int j = 1; j <= N + M;j++) {
int m = 1e9; int index = -1;
//find shortest distance
for (int k = 1; k <= N + M; k++) {
if (result[i][k] < m && s[k]==0) {
m = result[i][k]; index = k;
}
}
s[index] = 1;
for (int k = 1; k <= N + M; k++) {
if (s[k] == 0 && result[i][index] + d[index][k] < result[i][k])
result[i][k] = result[i][index] + d[index][k];
}
}
}
int min = 0; int index = -1; float ave = 0;
for (int i = 1; i <= M ; i++) {
int temp = 1e9; int s = 0; int flag = 1;
for (int j = 1; j <= N; j++) {
if (result[i][j] > Ds) {
flag = 0; break;
}
s += result[i][j];
if (result[i][j] < temp) temp = result[i][j];
}
if (flag == 0) continue;
if (temp > min) {
min = temp;
index = i;
ave = (float)s / N;
}
else if (temp == min) {
if ((float)s / N < ave) {
index = i;
ave = (float)s / N;
}
}
}
if (index == -1) cout << "No Solution";
else {
printf("G%d\n%.1f %.1f", index, (float)min, ave);
}
return 0;
}