lightoj 1018 （状态压缩DP）

#include<cstdio>
#include<string>
#include<cstring>
#include<iostream>
#include<algorithm>
using namespace std;
const int MAXN = 16;
int n, dp[1 << MAXN], s[MAXN][MAXN];
struct Point{
    int x, y;
    bool isOnLine(const Point &A, const Point &B){
        return (A.y-y)*(x-B.x) == (A.x-x)*(y-B.y);
    }
};
Point P[MAXN];
void init(){
    memset(dp, 0x3f, sizeof dp);
    memset(s, 0, sizeof s);
    for(int i = 0;i < n;i ++){
        for(int j = i+1;j < n;j ++){
            for(int k = 0;k < n;k ++){
                if(P[k].isOnLine(P[i], P[j]))
                    s[i][j] = s[j][i] |= (1 << k);
            }
        }
    }
}
int dfs(int st){
    if(dp[st] != 0x3f3f3f3f) return dp[st];
    int cnt = 0;
    for(int i = 0;i < n;i ++) if(st & (1 << i)) cnt++;
    if(cnt == 0) return 0;
    if(cnt <= 2) return dp[st] = 1;
    for(int i = 0;i < n;i ++){
        if(st & (1 << i)){
            for(int j = i + 1;j < n;j ++){
                if(st & (1 << j)){
                    dp[st] = min(dp[st], dfs(st - (st&s[i][j])) + 1);
                }
            }
            break;
        }
    }
    return dp[st];
}
int main(){
    int t, CASE(0);
    scanf("%d", &t);
    while(t--){
        scanf("%d", &n);
        for(int i = 0;i < n;i ++) scanf("%d%d", &P[i].x, &P[i].y);
        init();
        printf("Case %d: %d\n", ++CASE, dfs((1 << n)-1));
    }
    return 0;
}