poj 1054（注意審題和理解題意，只考慮超過三個腳印的青蛙，如果存在青蛙腳印，則必須是連續的，即按規律之前和之後都不能有空格）
阿新 • • 發佈：2021-11-23
#include<iostream> #include<algorithm> using namespace std; typedef struct node{ int x,y; }Point; Point point[5005]; int r,c,n; int qcmp(const void*a,const void*b){ Point *p1 = (Point*)a; Point *p2 = (Point*)b; if(p1->x>p2->x||(p1->x==p2->x&&p1->y>p2->y))return1; if(p1->x==p2->x&&p1->y==p2->y)return 0; return -1; } int cmp(Point p1,Point p2){ if(p1.x<p2.x||(p1.x==p2.x&&p1.y<p2.y))return true; return false; } bool isIn(int x,int y){ if(x<=0||x>r||y<=0||y>c)return false; return true; } boolsearch(int x,int y){ int mid,l = 0,r = n; while(l<=r){ mid = (l+r)/2; if(point[mid].x==x&&point[mid].y==y)return true; if(point[mid].x<x||(point[mid].x==x&&point[mid].y<y))l = mid+1; else r = mid-1; } return false; } int main(){ scanf("%d%d%d",&r,&c,&n); for(int i=0;i<n;i++){ scanf("%d%d",&point[i].x,&point[i].y); } // sort(point,point+n,cmp); qsort(point,n,sizeof(Point),qcmp); int max_num = 0; for(int i=0;i<n;i++){ for(int j=i+1;j<n;j++){ int x = point[j].x-point[i].x; int y = point[j].y-point[i].y; if(isIn(point[i].x-x,point[i].y-y)|| !isIn(point[i].x+max_num*x,point[i].y+max_num*y))continue; int num = 0; for(int k=1;isIn(point[j].x+k*x,point[j].y+k*y);k++){ if(search(point[j].x+k*x,point[j].y+k*y))num++; else{ num = 0; break; } } max_num = max(num,max_num); } } if(max_num)max_num += 2; printf("%d\n",max_num); return 0; }