'commit'

TangDou/AcWing/LIS/896_FenWickTree_1.cpp

@@ -0,0 +1,46 @@
+#include <bits/stdc++.h>
+using namespace std;
+#define lowbit(x) (x & -x)
+const int N = 1e5 + 10;
+
+int n, a[N];
+int b[N], bl; //离散化数组，用于辅助树状数组
+int c[N];     //树状数组
+int res;      //结果
+
+//计算x值在原序列中的排名
+int get(int x) {
+    return lower_bound(b, b + bl, x) - b + 1;
+}
+
+//单点更新x
+void update(int i, int x) {
+    for (; i <= bl; i += lowbit(i)) c[i] = max(c[i], x);
+}
+
+//求1~i的最大值
+int query(int i) {
+    int s = 0;
+    for (; i; i -= lowbit(i)) s = max(s, c[i]);
+    return s;
+}
+
+int main() {
+    scanf("%d", &n);
+    for (int i = 0; i < n; i++) scanf("%d", &a[i]), b[i] = a[i];
+
+    //离散化，用于获取 x值->排名k 的关系
+    sort(b, b + n);
+    // bl：去重后的长度
+    bl = unique(b, b + n) - b;
+
+    for (int i = 0; i < n; i++) {
+        int k = get(a[i]); //值a[i]的排名k
+        int t = query(k - 1) + 1;
+        res = max(res, t);
+        update(k, t); //第k大的数，会接在第k-1大的数后面，才会获取到更大的连续LIS值
+    }
+    //输出
+    printf("%d\n", res);
+    return 0;
+}