前缀和水题，没什么好讲的，注意横纵坐标加1。

另外此题空间有点紧。

 

代码实现如下：

#include 
      
       using namespace std;#define rep(i, a, b) for (register int i = (a); i <= (b); i++)const int maxn = 5e3 + 5;int n, m, N, R;int a[maxn][maxn];int MAX(int a, int b) {
    return a > b ? a : b;}int read() {    int x = 0, flag = 0;    char ch = ' ';    while (ch != '-' && (ch < '0' || ch > '9')) ch = getchar();    if (ch == '-') {        flag = 1;        ch = getchar();    }    while (ch >= '0' && ch <= '9') {        x = (x << 1) + (x << 3) + (ch ^ '0');        ch = getchar();    }    return flag ? -x : x;}void write(int x) {    if (x < 0) {        putchar('-');        x = -x;    }    if (x > 9) write(x / 10);    putchar(x % 10 + '0');}int main() {    N = read(), R = read();    n = R, m = R;    rep(i, 1, N) {        int x, y, w;        x = read(), y = read(), w = read();        x++, y++;        a[x][y] = w;        n = MAX(n, x);        m = MAX(m, y);    }    rep(i, 1, n)        rep(j, 1, m)            a[i][j] += a[i - 1][j] + a[i][j - 1] - a[i - 1][j - 1];    int ans = 0;    rep(i, R, n)        rep(j, R, m)            ans = MAX(ans, a[i][j] - a[i - R][j] - a[i][j - R] + a[i - R][j - R]);    write(ans);    return 0;}