'commit'

TangDou/AcWing/BIT/P3368_1.cpp

@@ -0,0 +1,42 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+const int N = 5e5 + 10;
+int a[N]; // a是原数组。c是差分数组，用树状数组维护
+
+int n, m;
+
+// 树状数组模板
+typedef long long LL;
+#define lowbit(x) (x & -x)
+int c[N];
+void add(int x, int d) {
+    for (int i = x; i < N; i += lowbit(i)) c[i] += d;
+}
+LL sum(int x) {
+    LL res = 0;
+    for (int i = x; i; i -= lowbit(i)) res += c[i];
+    return res;
+}
+
+int main() {
+    scanf("%d %d", &n, &m);
+
+    // 原数组
+    for (int i = 1; i <= n; i++) scanf("%d", &a[i]);
+
+    int op, l, r, v, k;
+    while (m--) {
+        scanf("%d", &op);
+        if (op == 1) {
+            scanf("%d %d %d", &l, &r, &v);
+            add(l, v), add(r + 1, -v);
+        } else {
+            scanf("%d", &k);
+            // 树状数组维护的是变化量，还需要加上原来的值
+            printf("%d\n", a[k] + sum(k)); // 求某点的值
+        }
+    }
+
+    return 0;
+}