HDU 4462 scaring The Birds (violence enumeration Dfs)

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Test instructions: A n*n area, where M can put the Scarecrow, the rest are corn. For each position (x, y) The Scarecrow has a scope ri,

That is, ABS (x-i) +abs (y-j) <=r, (I,J) is within the scope of the action. Ask at least a few places to put the Scarecrow to cover all the corn, if not possible output-1.

There is a trick, is to put the Scarecrow's position without being covered

eg

Input

2 4

1 1 1 2 2 1 2 2

0 0 0 0

Output

0 0

The code is as follows:

#include <iostream> #include <cstring> #include <cstdio> #include <cmath> #include <    algorithm>using namespace Std;const int maxn = 60;struct point{int x,y,wide;    Point () {} point (int _x,int _y): X (_x), Y (_y) {}}p[maxn];int mp[maxn][maxn];int n,k;bool check () {int tot=0;        for (int i=1;i<=n;i++) for (int j=1;j<=n;j++) {tot+= (mp[i][j]>0); } return tot==n*n;} BOOL Flag;void Modify (Point P,int wide,int val) {for (int i=max (1,p.x-wide), I<=min (n,p.x+wide); i++) for (int j=                Max (1,p.y-wide); J<=min (n,p.y+wide); j + +) {if (ABS (i-p.x) +abs (J-P.Y) <=wide&&mp[i][j]!=10000)        Mp[i][j]+=val;    }}void dfs (int num,int id,int tot) {if (tot>num) return;        if (tot==num) {if (check ()) flag=1;    Return } if (Flag| |    ID&GT;=K) return;    Modify (p[id],p[id].wide,1);    DFS (NUM,ID+1,TOT+1);    Modify (p[id],p[id].wide,-1); DFS (Num,id+1,tot);} int main () {while (~scanf ("%d", &n) &&n) {scanf ("%d", &k);            for (int i=0;i<k;i++) {int x, y;            scanf ("%d%d", &x,&y);            P[i]=point (x, y);        mp[x][y]=10000;        } for (int i=0;i<k;i++) {scanf ("%d", &p[i].wide);        } int ans = 100000000;            for (int i=0;i<=k;i++) {memset (Mp,0,sizeof (MP)); for (int j=0;j<k;j++) mp[p[j].x][p[j].y]=10000; '            \ ' \ flag = 0;            DFS (i,0,0);                if (flag) {ans = i;            Break        }} if (ans!=100000000) printf ("%d\n", ans);    else printf (" -1\n"); } return 0;} /***422 2 3 31 3422 2 3 31 42 41 1 1 2 2 1 2 20 0 0 0***/

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HDU 4462 scaring The Birds (violence enumeration Dfs)