diff --git "a/ShinHeeEul/202504/24 BOJ D5 \352\270\210\352\264\221.md" "b/ShinHeeEul/202504/24 BOJ D5 \352\270\210\352\264\221.md" new file mode 100644 index 00000000..60933781 --- /dev/null +++ "b/ShinHeeEul/202504/24 BOJ D5 \352\270\210\352\264\221.md" @@ -0,0 +1,145 @@ +```java +import java.util.*; +import java.io.*; + +class Main { + + static Node[] segments; + static long MIN = Long.MIN_VALUE >> 1; + static Node DEFAULT = new Node(MIN,MIN,MIN,0); + static int N; + static int size; + public static void main(String[] args) throws Exception { + + N = read(); + + size = 1; + + while(size < N) size <<= 1; + + + + // Point 별로 값을 저장해두고, x좌표 순으로 정렬 후 index 매기기 + Point[] arr = new Point[N]; + + for(int i = 0; i < N; i++) arr[i] = new Point(read(), read(), 0, read()); + + Arrays.sort(arr, (o1, o2) -> { + if(o1.x == o2.x) return o1.val - o2.val; + return o1.x - o2.x; + }); + + for(int i = 0; i < N; i++) { + arr[i].index = i; + int idx = i; + while((i + 1) < N && arr[i + 1].x == arr[i].x) { + arr[i + 1].index = idx; + i++; + } + } + // 이후 y좌표 순으로 정렬 후 + Arrays.sort(arr, Comparator.comparingInt(p -> p.y)); + + // y가 작은 것/큰 것부터 update하면서 해당 인덱스에 업데이트 + long max = Long.MIN_VALUE; + + + + int nxt = 1; + for(int k = 0; k < N; k+=nxt) { + nxt = 1; + while((k+nxt) < N && arr[k+nxt].y == arr[k].y) { + nxt++; + } + segments = new Node[(size << 1) + 1]; + Arrays.fill(segments, DEFAULT); + for (int i = k; i < N; i++) { + Point point = arr[i]; + update(point.index, point.val); + + // y가 같은 값이라면 한번에 업데이트 해야 함. + while ((i + 1) < N && arr[i + 1].y == point.y) { + update(arr[i + 1].index, arr[i + 1].val); + i++; + } + max = Math.max(max, segments[2].max); + } + } + + System.out.println(max); + } + + public static void update(int idx, int val) { + + idx += size + 1; + if(segments[idx] == DEFAULT) segments[idx] = new Node(val, val, val, val); + else { + segments[idx].lmax += val; + segments[idx].rmax += val; + segments[idx].max += val; + segments[idx].sum += val; + } + idx = (idx + 1) >> 1; + + while(idx >= 2) { + segments[idx] = combine(segments[(idx << 1) - 1], segments[idx << 1]); + idx = (idx + 1) >> 1; + } + } + + public static Node combine(Node lNode, Node rNode) { + return new Node( + Math.max(lNode.lmax, lNode.sum + rNode.lmax), + Math.max(rNode.rmax, rNode.sum + lNode.rmax), + Math.max(lNode.rmax + rNode.lmax, Math.max(lNode.max, rNode.max)), + lNode.sum + rNode.sum + ); + } + + public static class Point { + int x; + int y; + int index; + int val; + + public Point(int x, int y, int index, int val) { + this.x = x; + this.y = y; + this.index = index; + this.val = val; + } + } + + public static class Node { + long lmax; + long rmax; + long max; + long sum; + + public Node(long lmax, long rmax, long max, long sum) { + this.lmax = lmax; + this.rmax = rmax; + this.max = max; + this.sum = sum; + } + + } + + private static int read() throws Exception { + int d, o; + boolean negative = false; + d = System.in.read(); + if (d == 45) { + negative = true; + d = System.in.read(); + } + + o = d & 15; + while ((d = System.in.read()) > 32) + o = (o << 3) + (o << 1) + (d & 15); + + return negative ? -o : o; + } + +} +```