HDU 4739 求正方形个数

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九野的博客，转载请注明出处：http://blog.csdn.net/acmmmm/article/details/11711707

求所有可能围成的正方形，借个代码

#include <queue>#include <vector>#include <stack>#include <string>#include <cstdio>#include <math.h>#include <cstdlib>#include <string.h>#include <iostream>#include <fstream>#include <algorithm>using namespace std;#define LL long long#define PI acos(-1.0)#define N 5100#define M 1148576#define inf 1000000000struct node {    int a, b, c, d;    void set (int _a, int _b, int _c, int _d) {        a = _a; b = _b; c = _c; d = _d;    }}pe[N];struct point {    int x, y;    void set () {        scanf ("%d%d", &x, &y);    }}p[30];int cnt;int cmp (point a, point b) {    if (a.x == b.x) return a.y < b.y;    return a.x < b.x;}int dp[M];int dfs (int s) {    if (dp[s] != -1) return dp[s];    int Max = 0;    for (int i = 0; i < cnt; ++i) {        if ((s&(1<<pe[i].a)) + (s&(1<<pe[i].b))+(s&(1<<pe[i].c)) + (s&(1<<pe[i].d)) == 0) {            int si = s + (1<<pe[i].a) + (1<<pe[i].b) + (1<<pe[i].c) + (1<<pe[i].d);            Max = max (Max, dfs (si) + 4);        }    }    return dp[s]= Max;}int main () {    int n;    while (scanf ("%d", &n), n != -1) {        for (int i = 0; i < n; ++i) {            p[i].set();        }        cnt = 0;        sort (p, p + n, cmp);        for (int i = 0; i < n; ++i) {            for (int j = i + 1; j < n; ++j) {                if (p[i].x != p[j].x) break;                for (int ii = j + 1;  ii < n; ++ii) {                    for (int jj = ii + 1; jj < n; ++jj) {                        if (p[ii].x != p[jj].x) continue;                        if (p[i].y == p[ii].y && p[j].y == p[jj].y && p[j].y - p[i].y == p[ii].x - p[i].x) {                            pe[cnt].set (i, j, ii, jj);                        //    cout << i << ' ' << j << ' ' << ii << ' ' << jj << endl;                            cnt++;                        }                    }                }            }        }        memset (dp, -1, sizeof (dp));        printf ("%d\n", dfs (0));    }}