백준 14395번 4연산 C++

https://www.acmicpc.net/problem/14395

14395번: 4연산

 

bfs

 

#include <iostream>
#include <string>
#include <vector>
#include <math.h>
#include <algorithm>
#include <utility>
#include <stack>
#include <queue>
#include <math.h>
#include <set>
#include <map>
#include <list>
#include <unordered_map>
#include <unordered_set>
#include <iomanip>
#include <limits.h>

using namespace std;
using int64 = long long;

int64 s, t;

struct Info {
    int64 val;
    string ops;
};

set<int64> st;
char op[4] = { '*','+','-','/' };

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);

    cin >> s >> t;
    queue<Info> q;
    string ans = "?";
    q.push({ s,"" });
    st.insert(s);
    while (!q.empty()) {
        auto curr = q.front();
        q.pop();
        if (curr.val == t) {
            ans = curr.ops;
            break;
        }
        for (int i = 0; i < 4; i++) {
            char nextOp = op[i];
            int64 nextVal = curr.val;
            switch (nextOp) {
            case '*':
                nextVal *= curr.val;
                break;
            case '+':
                nextVal += curr.val;
                break;
            case '-':
                nextVal -= curr.val;
                break;
            case '/':
                if (curr.val != 0) {
                    nextVal /= curr.val;
                }
                break;
            }
            if (st.find(nextVal) != st.end()) continue;
            q.push({ nextVal,curr.ops + nextOp });
            st.insert(nextVal);
        }
    }
    if (ans == "") cout << 0;
    else if (ans == "?") cout << -1;
    else cout << ans;
}