MyLeetcode/cpp_solutions/1345.cpp at main · Kaminyou/MyLeetcode · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
class Solution {
public:
    int minJumps(vector<int>& arr) {
        unordered_map<int, vector<int>> mp;
        unordered_map<int, bool> mpUsed;
        int n = arr.size();
        for (int i = 0; i < n; ++i) {
            mp[arr[i]].push_back(i);
            mpUsed[arr[i]] = false;
        }

        vector<bool> visited(n, false);
        queue<int> q;
        q.push(0);
        visited[0] = true;

        int step = 0;
        while (!q.empty()) {
            int m = q.size();
            for (int i = 0; i < m; ++i) {
                int node = q.front();
                q.pop();
                if (node == n - 1) return step;
                if (node - 1 >= 0 && !visited[node - 1]) {
                    q.push(node - 1);
                    visited[node - 1] = true;
                }
                if (node + 1 < n && !visited[node + 1]) {
                    q.push(node + 1);
                    visited[node + 1] = true;
                }
                if (!mpUsed[arr[node]]) {
                    mpUsed[arr[node]] = true;
                    for (auto& neighbor : mp[arr[node]]) {
                        if (visited[neighbor]) continue;
                        q.push(neighbor);
                        visited[neighbor] = true;
                    }
                }
            }
            step++;
        }
        return -1;
    }
};

class Solution {
public:
    int minJumps(vector<int>& arr) {
        int n = arr.size();
        unordered_map<int, vector<int>> num2pos;
        for (int i = 0; i < n; ++i) {
            num2pos[arr[i]].push_back(i);
        }
        vector<bool> visited(n, false);
        queue<int> q;
        q.push(0);
        visited[0] = true;
        int res = 0;
        while (!q.empty()) {
            int m = q.size();
            while (m--) {
                int curr = q.front();
                q.pop();
                if (curr == n - 1) return res;
                int left = curr - 1;
                int right = curr + 1;
                if (left >= 0 && !visited[left]) {
                    q.push(left);
                    visited[left] = true;
                }
                if (right < n && !visited[right]) {
                    q.push(right);
                    visited[right] = true;
                }
                if (num2pos.count(arr[curr])) {
                    for (auto& pos : num2pos[arr[curr]]) {
                        if (!visited[pos]) {
                            q.push(pos);
                            visited[pos] = true;
                        }
                    }
                    num2pos.erase(arr[curr]);
                }
            }
            res++;
        }
        return -1;
    }
};