PAT甲级 1072（C++）

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;
}