算法训练营|图论第8天 拓扑排序 dijkstra

题目：

拓扑排序

题目链接：

117. 软件构建 (kamacoder.com)

代码：

#include<bits/stdc++.h>
#include<unordered_map>
using namespace std;
int main() {
	int n, m;
	cin >> n >> m;
	vector<int>inDegree(n, 0);
	unordered_map<int, vector<int>>myMap;
	vector<int>result;
	for (int i = 0; i < m; i++) {
		int s, t;
		cin >> s >> t;
		inDegree[t]++;
		myMap[s].push_back(t);
	}
	queue<int>que;
	for (int i = 0; i < n; i++) {
		if (inDegree[i] == 0) {
			que.push(i);
		}
	}
	while (!que.empty()) {
		int cur = que.front();
		que.pop();
		result.push_back(cur);
		vector<int>files = myMap[cur];
		if (files.size() != 0) {
			for (int i = 0; i < files.size(); i++) {
				inDegree[files[i]]--;
				if (inDegree[files[i]] == 0) {
					que.push(files[i]);
				}
			}
		}
	}
	if (result.size() == n) {
		for (int i = 0; i < n - 1; i++) {
			cout << result[i] << ' ';
		}
		cout << result[n - 1] << endl;
	}
	else {
		cout << -1 << endl;
	}
}

题目：

dijkstra

题目链接：

47. 参加科学大会（第六期模拟笔试） (kamacoder.com)

代码：

#include<bits/stdc++.h>
using namespace std;
int main() {
	int n, m, s, e, v;
	cin >> n >> m;
	vector<vector<int>>grid(n + 1, vector<int>(n + 1, INT_MAX));
	for (int i = 0; i < m; i++) {
		cin >> s >> e >> v;
		grid[s][e] = v;
	}
	vector<int>minDist(n + 1, INT_MAX);
	vector<bool>visited(n + 1, false);
	int start = 1;
	int end = n;
	minDist[start] = 0;
	for (int i = 1; i <= n; i++) {
		int minVal = INT_MAX;
		int cur = 1;
		for (int v = 1; v <= n; v++) {
			if (!visited[v] && minDist[v] < minVal) {
				cur = v;
				minVal = minDist[v];
			}
			visited[cur] = true;
			for (int v = 1; v <= n; v++) {
				if (!visited[v] && grid[cur][v] != INT_MAX && minDist[cur] + grid[cur][v] < minDist[v]) {
					minDist[v] = minDist[cur] + grid[cur][v];
				}
			}
		}
	}
	if (minDist[end] == INT_MAX) cout << -1 << endl;
	else {
		cout << minDist[end] << endl;
	}
}