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package class46;
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import java.util.TreeSet;
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public class Problem_0363_MaxSumOfRectangleNoLargerThanK {
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public static int nearK(int[] arr, int k) {
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if (arr == null || arr.length == 0) {
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return Integer.MIN_VALUE;
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}
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TreeSet<Integer> set = new TreeSet<>();
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set.add(0);
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int ans = Integer.MIN_VALUE;
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int sum = 0;
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for (int i = 0; i < arr.length; i++) {
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// 讨论子数组必须以i位置结尾，最接近k的累加和是多少？
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sum += arr[i];
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// 找之前哪个前缀和 >= sum - k 且最接近
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// 有序表中，ceiling(x) 返回>=x且最接近的！
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// 有序表中，floor(x) 返回<=x且最接近的！
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Integer find = set.ceiling(sum - k);
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if(find != null) {
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int curAns = sum - find;
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ans = Math.max(ans, curAns);
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}
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set.add(sum);
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}
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return ans;
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}
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public static int maxSumSubmatrix(int[][] matrix, int k) {
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if (matrix == null || matrix[0] == null) {
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return 0;
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}
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if (matrix.length > matrix[0].length) {
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matrix = rotate(matrix);
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}
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int row = matrix.length;
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int col = matrix[0].length;
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int res = Integer.MIN_VALUE;
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TreeSet<Integer> sumSet = new TreeSet<>();
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for (int s = 0; s < row; s++) {
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int[] colSum = new int[col];
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for (int e = s; e < row; e++) {
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// s ~ e 这些行 选的子矩阵必须包含、且只包含s行~e行的数据
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// 0 ~ 0 0 ~ 1 0 ~ 2 。。。
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// 1 ~ 2 1 ~ 2 1 ~ 3 。。。
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sumSet.add(0);
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int rowSum = 0;
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for (int c = 0; c < col; c++) {
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colSum[c] += matrix[e][c];
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rowSum += colSum[c];
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Integer it = sumSet.ceiling(rowSum - k);
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if (it != null) {
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res = Math.max(res, rowSum - it);
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}
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sumSet.add(rowSum);
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}
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sumSet.clear();
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}
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}
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return res;
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}
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public static int[][] rotate(int[][] matrix) {
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int N = matrix.length;
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int M = matrix[0].length;
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int[][] r = new int[M][N];
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for (int i = 0; i < N; i++) {
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for (int j = 0; j < M; j++) {
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r[j][i] = matrix[i][j];
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}
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}
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return r;
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}
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}
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