51nod 1100 斜率最大

#include <bits/stdc++.h>using namespace std;struct node{long long x,y,index;}arr[10010];bool cmp(node n1,node n2){if(n1.x!=n2.x)return n1.x<n2.x;return n1.y<n2.y;} vector<int> vec;int main(){long long n,i,dx,dy;while(cin>>n){for(i=0;i<n;i++){scanf("%lld%lld",&arr[i].x,&arr[i].y);arr[i].index=i+1;}sort(arr,arr+n,cmp);dx=1;dy=-(1<<30);vec.clear();for(i=0;i<n-1;i++){if((arr[i+1].y-arr[i].y)*dx>dy*(arr[i+1].x-arr[i].x)){vec.clear();dy=arr[i+1].y-arr[i].y;dx=arr[i+1].x-arr[i].x;}if((arr[i+1].y-arr[i].y)*dx==dy*(arr[i+1].x-arr[i].x)){vec.push_back(i);dy=arr[i+1].y-arr[i].y;dx=arr[i+1].x-arr[i].x;}}for(i=0;i<vec.size();i++){printf("%lld %lld\n",arr[vec[i]].index,arr[vec[i]+1].index);}}}