有点水：
/* ID: qq104801 LANG: C++ TASK: snail QQ:104804687 */ #include <iostream> #include <fstream> #include <cstring> #include <vector> #include <queue> #include <stack> #include <algorithm> #include <cmath> using namespace std; #define loop(i,n) for(int i=0;i<(n);i++) #define loop2(i,n) for(int i=1;i<=(n);i++) const int maxn=205; const int inf=1<<30; int n,m,k; int a[maxn][maxn]; int go[4][2]={{0,-1},{1,0},{0,1},{-1,0}}; int ans; void dfs(int y,int x,int turn,int step) { if(step-1>ans)ans=step-1; if(a[y][x]==1) { y-=go[turn][1]; x-=go[turn][0]; k=(turn+1)%4; if(!a[y+go[k][1]][x+go[k][0]]) dfs(y+go[k][1],x+go[k][0],k,step); k=(turn+3)%4; if(!a[y+go[k][1]][x+go[k][0]]) dfs(y+go[k][1],x+go[k][0],k,step); return; } if(a[y][x]==2)return; a[y][x]=2; dfs(y+go[turn][1],x+go[turn][0],turn,step+1); a[y][x]=0; } void test() { freopen("snail.in","r",stdin); freopen("snail.out","w",stdout); cin>>n>>m; for(int i=0;i<=n+1;i++)a[0][i]=a[n+1][i]=a[i][0]=a[i][n+1]=1; int ii; char c; while(m--) { cin>>c>>ii; a[ii][c-'A'+1]=1; } ans=0; dfs(1,1,1,1); dfs(1,1,2,1); cout<<ans<<endl; } int main () { test(); return 0; }
test data:
USACO Training Grader Results 6 users online CHN/2 MYS/1 NZL/1 TJK/1 USA/1 USER: cn tom [qq104801] TASK: snail LANG: C++ Compiling... Compile: OK Executing... Test 1: TEST OK [0.003 secs, 3536 KB] Test 2: TEST OK [0.005 secs, 3536 KB] Test 3: TEST OK [0.005 secs, 3536 KB] Test 4: TEST OK [0.008 secs, 3536 KB] Test 5: TEST OK [0.005 secs, 3536 KB] Test 6: TEST OK [0.005 secs, 3536 KB] Test 7: TEST OK [0.005 secs, 3536 KB] Test 8: TEST OK [0.005 secs, 3536 KB] Test 9: TEST OK [0.005 secs, 3536 KB] Test 10: TEST OK [0.011 secs, 3536 KB] Test 11: TEST OK [0.005 secs, 3536 KB] Test 12: TEST OK [0.041 secs, 3536 KB] All tests OK. YOUR PROGRAM ('snail') WORKED FIRST TIME! That's fantastic -- and a rare thing. Please accept these special automated congratulations. Here are the test data inputs: ------- test 1 [length 16 bytes] ---- 8 4 E2 A6 G1 F5 ------- test 2 [length 16 bytes] ---- 5 4 C1 B4 D5 E4 ------- test 3 [length 35 bytes] ---- 8 10 A3 B1 B6 C5 D2 E7 F4 G1 G6 H8 ------- test 4 [length 37 bytes] ---- 10 10 A2 A9 B2 C7 D4 F5 G8 H3 I10 J1 ------- test 5 [length 33 bytes] ---- 10 9 A9 B2 C7 D4 F5 G8 H3 I10 J1 ------- test 6 [length 48 bytes] ---- 10 14 A3 C1 B4 D2 C5 E3 D6 F4 E7 G5 F8 H6 G9 I7 ------- test 7 [length 81 bytes] ---- 15 22 I1 C2 M2 G3 K3 D5 N5 F6 J6 B7 H8 G9 I9 B10 N10 E11 K11 F13 J13 C14 M14 H15 ------- test 8 [length 67 bytes] ---- 15 18 I1 B2 N2 H3 C5 M5 H6 A7 O7 G9 I9 H10 A11 O11 G13 I13 A15 O15 ------- test 9 [length 76 bytes] ---- 20 20 C1 G1 K1 O1 S1 T1 A3 A7 A11 A15 A19 A20 E20 I20 M20 Q20 T5 T9 T13 T17 ------- test 10 [length 136 bytes] ---- 20 37 F1 I1 Q1 D2 O2 A3 L4 S4 P5 K6 A7 C7 E7 I7 K7 Q8 F9 Q9 J10 L10 E11 O11 I12 F13 K13 A14 P14 R14 P15 I16 E17 S17 F18 L18 T18 H19 E20 ------- test 11 [length 183 bytes] ---- 120 48 T1 B2 F3 R3 U3 L4 E5 J6 M6 D8 K8 F9 A11 C11 M10 L11 P6 R7 O8 Q9 N10 P11 M12 O13 L14 N15 K16 M17 J18 L19 I20 K21 H22 J23 G24 I25 F26 H27 E28 G29 D30 F31 C32 E33 B34 D35 A36 C37 ------- test 12 [length 271 bytes] ---- 120 72 A4 A8 A12 A16 A20 A24 C4 E6 F8 H10 I12 K14 L16 N18 O20 Q22 R24 S25 T26 D1 E2 F3 G4 G5 H6 I7 J8 J9 K10 L11 M12 M13 N14 O15 P16 P17 Q18 R19 S20 S21 T22 U23 V24 H2 J4 K6 M8 N10 P12 Q14 S16 T18 V20 Y2 Y6 Y10 Y14 Y18 Y22 Y26 Z3 Z5 Z7 Z9 Z11 Z13 Z15 Z17 Z19 Z21 Z23 Z25 Keep up the good work! Thanks for your submission!