【HDU1166】敌兵布阵（树状数组或线段树）

是一道树状数组的裸题，也可以说是线段树的对于单点维护的裸题。多做这种题目可以提高自己对基础知识的理解程度，很经典。

 

 1 #include <iostream>

 2 #include <cstring>

 3 #include <cstdlib>

 4 #include <cstdio>

 5 #include <numeric>

 6 #include <algorithm>

 7 #include <cmath>

 8 #include <cctype>

 9 #include <string>

10 using namespace std;

11 

12 

13 const int N = 50005;

14 int C[N];

15 

16 struct peo {

17     int x, v;

18 }P[N];

19 

20 int lowbit (int x) {

21     return x & -x;

22 }

23 

24 int sum (int x) {

25     int ret = 0;

26     while (x > 0) {

27         ret += C[x]; x -= lowbit(x);

28     }

29     return ret;

30 }

31 

32 void add (int x, int d) {

33     while (x <= 50000) {

34         C[x] += d; x += lowbit(x);

35     }

36 }

37 

38 int _sum (int d, int u) {

39     return sum(u) - sum(d - 1);

40 }

41 

42 int main () {

43     int T, n, cur = 0; scanf("%d", &T);

44     char op[10];

45     while (T --) {

46         memset(C, 0, sizeof(C));

47         memset(P, 0, sizeof(P));

48         scanf("%d", &n);

49         for (int i = 0 ; i < n; ++ i) {

50             scanf("%d", &P[i].v);

51             P[i].x = i + 1;

52             add (P[i].x, P[i].v);

53         }

54         //cout << sum(3) << endl;

55         printf("Case %d:\n", ++ cur);

56         while (scanf("%s", op)) {

57             if (op[0] == 'E') {

58                 break;

59             } else if (op[0] == 'Q') {

60                 int x, y;

61                 scanf("%d %d", &x, &y);

62                 cout << _sum(x, y) << endl;

63             } else if (op[0] == 'S') {

64                 int x, y;

65                 scanf("%d %d", &x, &y);

66                 add (x, -y);

67             } else if (op[0] == 'A') {

68                 int x, y;

69                 scanf("%d %d", &x, &y);

70                 add (x, y);

71             }

72         }

73     }

74     return 0;

75 }

 

 1 #include <iostream>

 2 #include <cstdio>

 3 #include <cstring>

 4 #include <vector>

 5 #include <cstring>

 6 #include <cstdlib>

 7 #include <cctype>

 8 #include <algorithm>

 9 #include <numeric>

10 

11 using namespace std;

12 

13 struct P{

14     int sum, l, r;

15 } node[150050];

16 

17 int n, num[50050] = {0};

18 

19 void build (int k, int l, int r) {

20     node[k].l = l, node[k].r = r;

21     if (l == r) {

22         node[k].sum = num[l];

23     } else {

24         build(2 * k, l, (l + r) / 2);

25         build(2 * k + 1, ((l + r) / 2) + 1, r);

26         node[k].sum = node[2 * k].sum + node[2 * k + 1].sum;

27     }

28 }

29 

30 void update(int k, int i, int x) {

31     if (node[k].l <= i && node[k].r >= i) {

32         node[k].sum += x;

33     }

34     if (node[k].l == node[k].r) {

35         return ;

36     }

37     if (i <= node[2 * k].r) {

38         update(2 * k, i, x);

39     }

40     else update(2 * k + 1, i, x);

41 }

42 

43 int query (int k, int l, int r) {

44     if (l == node[k].l && r == node[k].r) {

45         return node[k].sum;

46     }

47     if (r <= node[2 * k].r)  {

48         return query(2 * k, l, r);

49     }

50     if (l >= node[2 * k + 1].l) {

51         return query(2 * k + 1, l, r);

52     } else {

53         return query(2 * k, l, node[2 * k].r) + query(2 * k + 1, node[2 * k + 1].l, r);

54     }

55 }

56 

57 int main(){

58     int T;

59     scanf("%d",&T);

60     for (int z = 1; z <= T; ++ z) {

61         memset(num, 0, sizeof(num));

62         scanf("%d", &n);

63         for (int i = 1; i <= n; ++ i) {

64             scanf("%d",&num[i]);

65         }

66         build(1, 1, n);

67         char s[100];

68         printf("Case %d:\n",z);

69         while (scanf("%s", s)){

70             if (s[0] == 'E')    break;

71             if (s[0] == 'Q'){

72                 int a, b;

73                 scanf("%d%d" ,&a ,&b);

74                 printf("%d\n",query(1, a, b));

75             }

76             if (s[0] == 'A'){

77                 int a,x;

78                 scanf("%d%d", &a, &x);

79                 update(1, a, x);

80             }

81             if (s[0] == 'S') {

82                 int a,x;

83                 scanf("%d%d", &a, &x);

84                 update(1, a, -x);

85             }

86         }

87     }

88     return 0;

89 }