2 条题解
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1
#include <bits/stdc++.h> using namespace std; #define ls u << 1 #define rs u << 1 | 1 #define LL long long #define int long long #define PII pair <int, int> #define fi first #define se second #define pub push_back #define pob pop_back #define puf push_front #define pof pop_front #define lb lower_bound #define ub upper_bound #define i128 __int128 #define pcnt(x) __builtin_popcount(x) #define mem(a,goal) memset(a, (goal), sizeof(a)) #define rep(x,start,end) for(int x = (start) - ((start) > (end)); x != (end) - ((start) > (end)); ((start) < (end) ? x ++ : x --)) #define aLL(x) (x).begin(), (x).end() #define sz(x) (int)(x).size() const int INF = 998244353; const int mod = 1e9 + 7; const int N = 1010; int g[N][N], dis[N][N]; int dx[] = {0, 1, 0, -1}; int dy[] = {1, 0, -1, 0}; int n, m; void bfs(int a, int b) { memset(dis, -1, sizeof(dis)); dis[a][b] = 0; queue<PII> q; q.push({a, b}); while(q.size()) { PII t = q.front(); q.pop(); for(int i = 0; i < 4; ++ i) { int x = t.first + dx[i], y = t.second + dy[i]; if(x >= 0 && x < n && y >= 0 && y < m && dis[x][y] == -1 && g[x][y] == 0) { dis[x][y] = dis[t.first][t.second] + 1; q.push({x, y}); } } } cout << dis[n - 1][m - 1] << '\n'; } void solve() { scanf("%lld%lld", &n, &m); for(int i = 0; i < n; ++ i) for(int j = 0; j < m; ++ j) scanf("%lld", &g[i][j]); bfs(0, 0); } signed main() { int t = 1; while (t --) solve(); return 0; }
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bfs
#include <iostream> #include <vector> #include <algorithm> #include <queue> #include <deque> #include <unordered_map> #include <map> #include <cstring> #include <cmath> #include <unordered_set> #include <set> #include <utility> #include <climits> #include <iomanip> #include <stack> #include <bitset> #define int long long #define PII pair<int, int> #define TLLL tuple<int , int , int> #define INF 0x3f3f3f3f3f3f3f3f #define all(v) v.begin() + 1 , v.end() #define ALL(v) v.begin() , v.end() #define endl "\n" using namespace std; const int N = 1e3 + 10; int n , m; int g[N][N] , dist[N][N]; bool st[N][N]; int dx[] = {0 , 1 , 0 , -1} , dy[] = {1 , 0 , -1 , 0}; //四个方向 void bfs(int sx , int sy) { queue<PII> q; q.push({sx , sy}); st[sx][sy] = true; while (q.size()) { auto t = q.front(); q.pop(); int x = t.first , y = t.second; for (int i = 0 ; i < 4 ; i ++ ) { int xx = dx[i] + x , yy = dy[i] + y; if (xx < 1 || xx > n || yy < 1 || yy > m || g[xx][yy]) continue; if (st[xx][yy]) continue; st[xx][yy] = true; dist[xx][yy] = dist[x][y] + 1; q.push({xx , yy}); if (xx == n && yy == m) return ; } } } void solve() { cin >> n >> m; for (int i = 1 ; i <= n ; i ++ ) for (int j = 1 ; j <= m ; j ++ ) cin >> g[i][j]; bfs(1 , 1); cout << dist[n][m] << endl; return ; } signed main() { ios::sync_with_stdio(false); cin.tie(nullptr), cout.tie(nullptr); int T = 1; while (T -- ) solve(); return 0; } ref(APA): yxy.千纸雏鸢-My Personal May.https://m.qzcy2.top. Retrieved 2025/9/9.
dijkstra
#include <iostream> #include <vector> #include <algorithm> #include <queue> #include <deque> #include <unordered_map> #include <map> #include <cstring> #include <cmath> #include <unordered_set> #include <set> #include <utility> #include <climits> #include <iomanip> #include <stack> #include <bitset> #define int long long #define PII pair<int, int> #define TLLL tuple<int , int , int> #define INF 0x3f3f3f3f3f3f3f3f #define inf 0x3f #define all(v) v.begin() + 1 , v.end() #define ALL(v) v.begin() , v.end() #define endl "\n" using namespace std; const int N = 4e6 + 10; int e[N] , ne[N] , h[N] , idx , dist[N]; bool st[N]; //链式前向星存图,相关概念可以参考过往文章->图论基础-透析链式前向星 inline void add(int a , int b) { e[idx] = b , ne[idx] = h[a] , h[a] = idx ++; } //将二维坐标转化为一维(即:从上到下,从左到右,依次编号为1,2,3,...,n * m)。 inline int transIndex(int a , int b , int m) { return (a - 1) * m + b; } //dijkstra void dijkstra() { memset(st , false , sizeof st); memset(dist , inf , sizeof dist); priority_queue<PII , vector<PII> , greater<PII> > heap; heap.push({0 , 1}); dist[1] = 0; st[1] = true; while (heap.size()) { auto t = heap.top(); heap.pop(); int distance = t.first , index = t.second; for (int i = h[index] ; ~i ; i = ne[i]) { int j = e[i]; if (dist[j] > distance + 1) { dist[j] = distance + 1; heap.push({ dist[j] , j}); } } } return ; } //函数本体 void solve() { int n , m; cin >> n >> m; vector<vector<int> > g(n + 1 , vector<int>(m + 1)); for (int i = 1 ; i <= n ; i ++ ) for (int j = 1 ; j <= m ; j ++ ) cin >> g[i][j]; memset(h , -1 , sizeof h); int dx[] = {0 , 1 , 0 , -1} , dy[] = {1 , 0 , -1 , 0}; //四个方向 //坐标转换 for (int i = 1 ; i <= n ; i ++ ) { for (int j = 1 ; j <= m ; j ++ ) { if (g[i][j]) continue; int u = transIndex(i , j , m); for (int k = 0 ; k < 4 ; k ++ ) { int x = i + dx[k] , y = j + dy[k]; if (x < 1 || x > n || y < 1 || y > m || g[x][y]) continue; int v = transIndex(x , y , m); add(u , v) , add(v , u); //题目描述可以上下左右,即 双向图 } } } dijkstra(); int end = transIndex(n , m , m); cout << dist[end] << endl; return ; } signed main() { ios::sync_with_stdio(false); cin.tie(nullptr), cout.tie(nullptr); int T = 1; // cin >> T; while (T -- ) solve(); return 0; } ref(APA): yxy.千纸雏鸢-My Personal May.https://m.qzcy2.top. Retrieved 2025/9/9.
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信息
- ID
- 90
- 时间
- 1000ms
- 内存
- 256MiB
- 难度
- 9
- 标签
- 递交数
- 15
- 已通过
- 4
- 上传者