HDU 4374 One hundred layer（单调队列+DP）

#include <iostream>
#include <cstring>
#include <cstdio>
#include <algorithm>
#include <cmath>

using namespace std;

const int maxn = 111;
const int maxm = 10010;
const int oo = 1 << 30;
int n, m, x, t;
int s[maxn][maxm];
int sum[maxn][maxm];
int dp[maxn][maxm];
int head, tail;
int myque[maxm][2];

int SUM(int i, int j, int k)
{
if (j > k) {
return 0;
}
return sum[i][k] - sum[i][j-1];
}

int main()
{
while (scanf("%d%d%d%d", &n, &m, &x, &t) != EOF) {
for (int i = 1; i <= n; ++i) {
sum[i][0] = 0;
for (int j = 1; j <= m; ++j) {
scanf("%d", &s[i][j]);
sum[i][j] = sum[i][j-1] + s[i][j];
dp[i][j] = -oo;
}
}
for (int i = x; i >= x - t && i >= 1; --i) {
dp[1][i] = sum[1][x] - sum[1][i-1];
}
for (int i = x; i <= x + t && i <= m; ++i) {
dp[1][i] = sum[1][i] - sum[1][x-1];
}
for (int i = 2; i <= n; ++i) {
// 从上一层的左边到达本层
head = tail = 0;
for (int j = 1; j <= m; ++j) {
while (head != tail && myque[tail-1][1] <= dp[i-1][j] - SUM(i, 1, j - 1)) {
tail--;
}
myque[tail][0] = j;
myque[tail][1] = dp[i-1][j] - SUM(i, 1, j - 1);
tail++;
while (j - myque[head][0] > t) {
head++;
}
dp[i][j] = max(dp[i][j], myque[head][1] + SUM(i, 1, j));
}
// 从上一层的右边到达本层
head = tail = 0;
for (int j = m; j >= 1; --j) {
while (head != tail && myque[tail-1][1] <= dp[i-1][j] + SUM(i, 1, j)) {
tail--;
}
myque[tail][0] = j;
myque[tail][1] = dp[i-1][j] + SUM(i, 1, j);
tail++;
while (myque[head][0] - j > t) {
head++;
}
dp[i][j] = max(dp[i][j], myque[head][1] - SUM(i, 1, j - 1));
}
}
int ans = -oo;
for (int i = 1; i <= m; ++i) {
ans = max(ans, dp
[i]);
}
printf("%d\n", ans);
}
return 0;
}