hdu1937 Finding Seats

hdu1937 Finding Seats

题意是 求最小的矩形覆盖面积内包含 k 个 空位置

枚举上下边界然后 双端队列 求 最小面积

#include <iostream>

#include <cstring>

#include <cstdio>

#include <cmath>

#include <algorithm>

#include <vector>

#include <map>

#include <queue>

#include <stack>

#include <set>

#include <string>

using namespace std;

typedef long long ll;

const double ESP = 10e-8;

const int MOD = 1000000000+7;

const int MAXN = 300+10;

char graph[MAXN][MAXN];

int sum[MAXN][MAXN];



int main(){

   // freopen("input.txt","r",stdin);

    int R,C,K;

    while(scanf("%d%d%d",&R,&C,&K)){

        if(!R && !C && !K){

            break;

        }

        for(int i = 0;i < R;i++){

            scanf("%s",graph[i]);

        }

        memset(sum,0,sizeof(sum));

        for(int i = 1;i <= R;i++){

            for(int j = 1;j <= C;j++){

                sum[i][j] = sum[i][j-1];

                sum[i][j] += sum[i-1][j] - sum[i-1][j-1];

                if(graph[i-1][j-1] == '.'){

                    sum[i][j]++;

                }

            }

        }

        int ans = R * C;

        for(int x2 = R;x2 > 0;x2--){

            if(sum[x2][C] < K){

                break;

            }

            for(int x1 = 1;x1 <= R;x1++){

                if(sum[x2][C] - sum[x1-1][C] < K){

                    break;

                }

                int y1 = 1;

                int y2 = 1;

                while(y1 <= C && y2 <= C){

                    int cnt = sum[x2][y2]-sum[x1-1][y2]-

                    (sum[x2][y1-1] - sum[x1-1][y1-1]);

                    if(cnt < K){

                        y2++;

                    }else{

                        ans = min(ans,(x2-x1+1)*(y2-y1+1));

                        y1++;

                        if(y1 > y2){

                            break;

                        }

                    }

                }

            }

        }

        printf("%d\n",ans);

    }

    return 0;

}

upc3111 star 

跟上面是类似的题，今年省赛的题 T_T

求最小矩形面积覆盖的 星星数 至少 为 k 个

就跟上面一样的题型了23333

#include <iostream>

#include <cstring>

#include <cstdio>

#include <cmath>

#include <algorithm>

#include <vector>

#include <map>

#include <queue>

#include <stack>

#include <set>

#include <string>

using namespace std;

typedef long long ll;

const double ESP = 10e-8;

const int MOD = 1000000000+7;

const int MAXN = 400+10;

int graph[MAXN][MAXN];

int sum[MAXN][MAXN];

int main(){

    //freopen("input.txt","r",stdin);

    int t;

    scanf("%d",&t);

    while(t--){

        int n,k;

        scanf("%d%d",&n,&k);

        memset(graph,0,sizeof(graph));

        memset(sum,0,sizeof(sum));

        int stX = 400,edX = 1,stY = 400,edY = 1;

        while(n--){

            int a,b;

            scanf("%d%d",&a,&b);

            graph[a][b]++;

            stX = min(a,stX);

            stY = min(b,stY);

            edX = max(a,edX);

            edY = max(b,edY);

        }

        for(int i = stX;i <= edX;i++){

            for(int j = stY;j <= edY;j++){

                sum[i][j] = sum[i-1][j] + sum[i][j-1] - sum[i-1][j-1];

                sum[i][j] += graph[i][j];

            }

        }

 

        int ans = (edX-stX+1)*(edY-stY+1);

        for(int x2 = edX;x2 >= stX;x2--){

            if(sum[x2][edY] < k){

                break;

            }

            for(int x1 = stX;x1 <= edX;x1++){

                if(sum[x2][edY] - sum[x1-1][edY] < k){

                    break;

                }

                int y1 = stY;

                int y2 = stY;

                while(y1 <= edY && y2 <= edY){

                    int cnt = sum[x2][y2] - sum[x2][y1-1]-(sum[x1-1][y2]-sum[x1-1][y1-1]);

                    if(cnt < k){

                        y2++;

                    }else{

                        ans = min(ans,(x2-x1+1)*(y2-y1+1));

                        y1++;

                        if(y1 > y2){

                            break;

                        }

                    }

                }

            }

        }

        printf("%d\n",ans);

    }

    return 0;

}