Submission #1074478

#	Submission time	Handle	Problem	Language	Result	Execution time	Memory
1074478	2024-08-25T10:43:58 Z	TheEpicCowOfLife	Mecho (IOI09_mecho)	C++14	100 / 100	239 ms	3404 KB

mecho

    #include <cstdio>
    #include <queue>
    #include <vector>
    #include <algorithm>
    #include <utility>
    #include <cstring>
     
    using namespace std;
     
    typedef pair<int,int> pii;
     
    bool is_g[805][805];
    bool pushed[805][805];
     
    bool bocc[805][805];
     
    int sx, sy;
    int fx, fy;
     
    int n,s;
     
    vector<pii> hv;
     
    queue<pii> mq;
    queue<pii> bq;
     
    int ax[4] = {0,1,0,-1};
    int ay[4] = {1,0,-1,0};
    // can mecho make it back to the hive waiting k minutes?
    bool decision(int k){
        queue<pii> mq;
        queue<pii> bq;
        memset(pushed, 0, sizeof(pushed));
        memset(bocc, 0, sizeof(bocc));
        mq.push({sx,sy});
        pushed[sx][sy] = true;
        for (pii cur : hv){
            bq.push(cur);
            bocc[cur.first][cur.second] = true;
        }
     
        for (int vi = 0; vi < k; vi++){
            int sz = bq.size();
            for (int i = 0 ; i < sz; i++){
                pii cur = bq.front();
                bq.pop();
                for (int j = 0; j < 4; j++){
                    int cx = cur.first + ax[j];
                    int cy = cur.second + ay[j];
                    if (!bocc[cx][cy] && is_g[cx][cy]){
                        bocc[cx][cy] = true;
                        bq.push({cx,cy});
                    }
                }
            }
        }
     
        while(true){
            int sz;
            for (int vi = 0; vi < s; vi++){
                sz = mq.size();
                for (int i = 0 ; i < sz; i++){
                    pii cur = mq.front();
                    mq.pop();
                    if (bocc[cur.first][cur.second]) continue;
                    for (int j = 0; j < 4; j++){
                        int cx = cur.first + ax[j];
                        int cy = cur.second + ay[j];
                        if (cx == fx && cy == fy) return true;
                        if (!bocc[cx][cy] && is_g[cx][cy] && !pushed[cx][cy]){
                            pushed[cx][cy] = true;
                            mq.push({cx,cy});
                        }
                    }
                }
            }
            if (sz == 0) return false;
            sz = bq.size();
            for (int i = 0 ; i < sz; i++){
                pii cur = bq.front();
                bq.pop();
                for (int j = 0; j < 4; j++){
                    int cx = cur.first + ax[j];
                    int cy = cur.second + ay[j];
                    if (!bocc[cx][cy] && is_g[cx][cy]){
                        bocc[cx][cy] = true;
                        bq.push({cx,cy});
                    }
                }
            }
        }
     
    }
     
    int main(){
        scanf("%d %d", &n, &s);
        for (int y = 1; y <= n; y++){
            for (int x = 1; x <= n; x++){
                char inst;
                scanf(" %c", &inst);
                if (inst == 'G'){
                    is_g[x][y] = true;
                }
                else if (inst == 'H'){
                    hv.push_back({x,y});
                }
                else if (inst == 'M'){
                    sx = x;
                    sy = y;
                    is_g[x][y] = true;
                }
                else if (inst == 'D'){
                    fx = x;
                    fy = y;
                }
            }
        }
     
        int best = -1;
        int lo = 0;
        int hi = n * n/2 + 1;
        while (lo <= hi){
            int mid = (lo + hi)/2;
            if (decision(mid)){
                lo = mid + 1;
                best = mid;
            }
            else{
                hi = mid - 1;
            }
        }
     
        printf("%d\n", best);
     
    }

Compilation message

mecho.cpp: In function 'int main()':
mecho.cpp:96:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   96 |         scanf("%d %d", &n, &s);
      |         ~~~~~^~~~~~~~~~~~~~~~~
mecho.cpp:100:22: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  100 |                 scanf(" %c", &inst);
      |                 ~~~~~^~~~~~~~~~~~~~
mecho.cpp: In function 'bool decision(int)':
mecho.cpp:77:13: warning: 'sz' may be used uninitialized in this function [-Wmaybe-uninitialized]
   77 |             if (sz == 0) return false;
      |             ^~

Subtask #1

100.0 / 100.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	1 ms	1716 KB	Output is correct
2	Correct	1 ms	1624 KB	Output is correct
3	Correct	1 ms	1628 KB	Output is correct
4	Correct	1 ms	1672 KB	Output is correct
5	Correct	1 ms	1628 KB	Output is correct
6	Correct	1 ms	1628 KB	Output is correct
7	Correct	180 ms	3056 KB	Output is correct
8	Correct	1 ms	1624 KB	Output is correct
9	Correct	1 ms	1624 KB	Output is correct
10	Correct	1 ms	1624 KB	Output is correct
11	Correct	1 ms	1628 KB	Output is correct
12	Correct	2 ms	1624 KB	Output is correct
13	Correct	2 ms	1628 KB	Output is correct
14	Correct	2 ms	1628 KB	Output is correct
15	Correct	1 ms	1628 KB	Output is correct
16	Correct	1 ms	1628 KB	Output is correct
17	Correct	1 ms	1624 KB	Output is correct
18	Correct	1 ms	1628 KB	Output is correct
19	Correct	2 ms	1624 KB	Output is correct
20	Correct	1 ms	1628 KB	Output is correct
21	Correct	2 ms	1628 KB	Output is correct
22	Correct	1 ms	1628 KB	Output is correct
23	Correct	1 ms	1628 KB	Output is correct
24	Correct	1 ms	1712 KB	Output is correct
25	Correct	2 ms	1628 KB	Output is correct
26	Correct	1 ms	1628 KB	Output is correct
27	Correct	2 ms	1628 KB	Output is correct
28	Correct	2 ms	1628 KB	Output is correct
29	Correct	2 ms	1628 KB	Output is correct
30	Correct	3 ms	1628 KB	Output is correct
31	Correct	1 ms	1628 KB	Output is correct
32	Correct	2 ms	1628 KB	Output is correct
33	Correct	19 ms	1888 KB	Output is correct
34	Correct	17 ms	2100 KB	Output is correct
35	Correct	37 ms	2112 KB	Output is correct
36	Correct	24 ms	2140 KB	Output is correct
37	Correct	34 ms	2392 KB	Output is correct
38	Correct	26 ms	2140 KB	Output is correct
39	Correct	44 ms	2020 KB	Output is correct
40	Correct	34 ms	2136 KB	Output is correct
41	Correct	46 ms	2136 KB	Output is correct
42	Correct	47 ms	2136 KB	Output is correct
43	Correct	53 ms	2140 KB	Output is correct
44	Correct	46 ms	2136 KB	Output is correct
45	Correct	56 ms	2412 KB	Output is correct
46	Correct	40 ms	2408 KB	Output is correct
47	Correct	85 ms	2408 KB	Output is correct
48	Correct	62 ms	2396 KB	Output is correct
49	Correct	48 ms	2396 KB	Output is correct
50	Correct	107 ms	2396 KB	Output is correct
51	Correct	97 ms	2396 KB	Output is correct
52	Correct	56 ms	2396 KB	Output is correct
53	Correct	74 ms	2392 KB	Output is correct
54	Correct	89 ms	2496 KB	Output is correct
55	Correct	108 ms	2644 KB	Output is correct
56	Correct	90 ms	2652 KB	Output is correct
57	Correct	120 ms	2644 KB	Output is correct
58	Correct	83 ms	2828 KB	Output is correct
59	Correct	109 ms	2828 KB	Output is correct
60	Correct	106 ms	2844 KB	Output is correct
61	Correct	103 ms	2900 KB	Output is correct
62	Correct	148 ms	2896 KB	Output is correct
63	Correct	239 ms	2940 KB	Output is correct
64	Correct	209 ms	2900 KB	Output is correct
65	Correct	188 ms	2844 KB	Output is correct
66	Correct	215 ms	2944 KB	Output is correct
67	Correct	220 ms	2944 KB	Output is correct
68	Correct	204 ms	2972 KB	Output is correct
69	Correct	189 ms	2972 KB	Output is correct
70	Correct	186 ms	2840 KB	Output is correct
71	Correct	215 ms	2956 KB	Output is correct
72	Correct	229 ms	2980 KB	Output is correct
73	Correct	169 ms	3244 KB	Output is correct
74	Correct	169 ms	3244 KB	Output is correct
75	Correct	179 ms	3228 KB	Output is correct
76	Correct	174 ms	3248 KB	Output is correct
77	Correct	165 ms	3020 KB	Output is correct
78	Correct	224 ms	3404 KB	Output is correct
79	Correct	181 ms	3216 KB	Output is correct
80	Correct	172 ms	3160 KB	Output is correct
81	Correct	215 ms	2976 KB	Output is correct
82	Correct	181 ms	3156 KB	Output is correct
83	Correct	226 ms	3156 KB	Output is correct
84	Correct	172 ms	3160 KB	Output is correct
85	Correct	192 ms	3164 KB	Output is correct
86	Correct	173 ms	3164 KB	Output is correct
87	Correct	208 ms	3164 KB	Output is correct
88	Correct	182 ms	2904 KB	Output is correct
89	Correct	172 ms	2896 KB	Output is correct
90	Correct	194 ms	2908 KB	Output is correct
91	Correct	183 ms	3112 KB	Output is correct
92	Correct	198 ms	2900 KB	Output is correct