Submission #1074369

#	Submission time	Handle	Problem	Language	Result	Execution time	Memory
1074369	2024-08-25T10:07:56 Z	TheEpicCowOfLife	Mecho (IOI09_mecho)	C++14	100 / 100	219 ms	3360 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:96:10: 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:100:18: 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:77:9: 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	1628 KB	Output is correct
2	Correct	1 ms	1628 KB	Output is correct
3	Correct	1 ms	1628 KB	Output is correct
4	Correct	1 ms	1628 KB	Output is correct
5	Correct	1 ms	1656 KB	Output is correct
6	Correct	1 ms	1628 KB	Output is correct
7	Correct	165 ms	2976 KB	Output is correct
8	Correct	1 ms	1624 KB	Output is correct
9	Correct	1 ms	1628 KB	Output is correct
10	Correct	1 ms	1624 KB	Output is correct
11	Correct	1 ms	1628 KB	Output is correct
12	Correct	1 ms	1628 KB	Output is correct
13	Correct	2 ms	1688 KB	Output is correct
14	Correct	3 ms	1756 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	1628 KB	Output is correct
18	Correct	1 ms	1560 KB	Output is correct
19	Correct	1 ms	1696 KB	Output is correct
20	Correct	1 ms	1628 KB	Output is correct
21	Correct	1 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	1628 KB	Output is correct
25	Correct	1 ms	1628 KB	Output is correct
26	Correct	2 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	2 ms	1728 KB	Output is correct
31	Correct	2 ms	1628 KB	Output is correct
32	Correct	2 ms	1624 KB	Output is correct
33	Correct	19 ms	1880 KB	Output is correct
34	Correct	15 ms	1884 KB	Output is correct
35	Correct	20 ms	1884 KB	Output is correct
36	Correct	24 ms	2140 KB	Output is correct
37	Correct	21 ms	2136 KB	Output is correct
38	Correct	26 ms	2136 KB	Output is correct
39	Correct	32 ms	2140 KB	Output is correct
40	Correct	26 ms	2260 KB	Output is correct
41	Correct	34 ms	2136 KB	Output is correct
42	Correct	41 ms	2148 KB	Output is correct
43	Correct	33 ms	2476 KB	Output is correct
44	Correct	44 ms	2148 KB	Output is correct
45	Correct	48 ms	2400 KB	Output is correct
46	Correct	40 ms	2408 KB	Output is correct
47	Correct	51 ms	2404 KB	Output is correct
48	Correct	58 ms	2396 KB	Output is correct
49	Correct	44 ms	2392 KB	Output is correct
50	Correct	62 ms	2396 KB	Output is correct
51	Correct	74 ms	2604 KB	Output is correct
52	Correct	54 ms	2392 KB	Output is correct
53	Correct	74 ms	2392 KB	Output is correct
54	Correct	79 ms	2640 KB	Output is correct
55	Correct	65 ms	2500 KB	Output is correct
56	Correct	85 ms	2724 KB	Output is correct
57	Correct	98 ms	2652 KB	Output is correct
58	Correct	78 ms	2900 KB	Output is correct
59	Correct	112 ms	2648 KB	Output is correct
60	Correct	104 ms	2936 KB	Output is correct
61	Correct	105 ms	2900 KB	Output is correct
62	Correct	126 ms	2940 KB	Output is correct
63	Correct	187 ms	2708 KB	Output is correct
64	Correct	204 ms	2904 KB	Output is correct
65	Correct	185 ms	2960 KB	Output is correct
66	Correct	196 ms	2940 KB	Output is correct
67	Correct	212 ms	3160 KB	Output is correct
68	Correct	200 ms	2968 KB	Output is correct
69	Correct	180 ms	2976 KB	Output is correct
70	Correct	183 ms	2900 KB	Output is correct
71	Correct	219 ms	2976 KB	Output is correct
72	Correct	217 ms	2904 KB	Output is correct
73	Correct	156 ms	3024 KB	Output is correct
74	Correct	160 ms	3232 KB	Output is correct
75	Correct	181 ms	3152 KB	Output is correct
76	Correct	173 ms	3244 KB	Output is correct
77	Correct	172 ms	3252 KB	Output is correct
78	Correct	170 ms	3008 KB	Output is correct
79	Correct	163 ms	3212 KB	Output is correct
80	Correct	181 ms	3360 KB	Output is correct
81	Correct	177 ms	3204 KB	Output is correct
82	Correct	167 ms	3160 KB	Output is correct
83	Correct	168 ms	3152 KB	Output is correct
84	Correct	169 ms	3164 KB	Output is correct
85	Correct	180 ms	3156 KB	Output is correct
86	Correct	166 ms	3164 KB	Output is correct
87	Correct	164 ms	3160 KB	Output is correct
88	Correct	167 ms	2904 KB	Output is correct
89	Correct	162 ms	2904 KB	Output is correct
90	Correct	168 ms	2992 KB	Output is correct
91	Correct	194 ms	3104 KB	Output is correct
92	Correct	211 ms	2900 KB	Output is correct