Hdu 2888 Check Corners (RMQ), hdurmq

Hdu 2888 Check Corners (RMQ), hdurmq

Link: hdu 2888 Check Corners

Given a matrix, the maximum value in the matrix is queried each time, and whether the maximum value is located in the corner of the query.

Solution: When a line segment tree is used, one-dimensional RMQ times out and is replaced with two-dimensional RMQ. As a result, MLE and dp arrays change to 9, 9, and 9.

#include <cstdio>#include <cstring>#include <algorithm>using namespace std;const int maxn = 305;int N, M, Q, g[maxn][maxn], dp[maxn][maxn][9][9];void rmq_init(int n, int m) {    for (int i = 1; i <= n; i++) {        for (int j = 1; j <= m; j++)            dp[i][j][0][0] = g[i][j];    }    for (int x = 0; (1<<x) <= n; x++)        for (int y = 0; (1<<y) <= m; y++)            if (x + y)                for (int i = 1; i + (1<<x) - 1 <= n; i++)                    for (int j = 1; j + (1<<y) - 1 <= m; j++) {                        if (x)                            dp[i][j][x][y] = max(dp[i][j][x-1][y], dp[i+(1<<(x-1))][j][x-1][y]);                        else                            dp[i][j][x][y] = max(dp[i][j][x][y-1], dp[i][j+(1<<(y-1))][x][y-1]);                    }}int rmq_query(int x1, int y1, int x2, int y2) {    int x = 0, y = 0;    while ((1<<(x+1)) <= x2 - x1 + 1) x++;    while ((1<<(y+1)) <= y2 - y1 + 1) y++;    x2 = x2 - (1<<x) + 1;    y2 = y2 - (1<<y) + 1;    return max( max(dp[x1][y1][x][y], dp[x2][y1][x][y]), max(dp[x1][y2][x][y], dp[x2][y2][x][y]));}int main () {    while (scanf("%d%d", &N, &M) == 2) {        for (int i = 1; i <= N; i++) {            for (int j = 1; j <= M; j++)                scanf("%d", &g[i][j]);        }        rmq_init(N, M);        scanf("%d", &Q);        int x1, y1, x2, y2;        while (Q--) {            scanf("%d%d%d%d", &x1, &y1, &x2, &y2);            int ans = rmq_query(x1, y1, x2, y2);            bool flag = false;            if (ans == g[x1][y1] || ans == g[x1][y2] || ans == g[x2][y1] || ans == g[x2][y2])                flag = true;            printf("%d %s\n", ans, flag ? "yes" : "no");        }    }    return 0;}

The common algorithm used to teach ACM is cainiao.

Good post. Pin it down.

First, you must learn a computer language, and then learn data structures and algorithms.

Finally, you need to exercise more on your own.