python/TangDou/Bfs/Test.cpp

#include <bits/stdc++.h>

using namespace std;
int a, b;
const int N = 10010;
bool st[N];
typedef pair<int, int> PII;
void bfs() {
    queue<PII> q; // q.first 当前是哪个数 q.second 从出发点到q.first走了几步
    q.push({a, 0});
    st[a] = true;
    while (q.size()) {
        auto t = q.front();
        q.pop();
        int u = t.first;
        int d = t.second;
        if (u == b) {
            cout << d << endl;
            exit(0);
        }
        if (!st[u + 1]) q.push({u + 1, d + 1});
        if (!st[u * 2]) q.push({u * 2, d + 1});
    }
}

int main() {
    cin >> a >> b;
    bfs();
    return 0;
}