HDU - 1166 敌兵布阵

题目链接 :

题目大意：

数据范围 :

解题思路：

//线段树--单点修改,区间求和
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <algorithm>
#include <set>
#include <map>
#include <queue>
using namespace std;
typedef long long LL;
const int inf = 1 << 30;
const LL INF = 1LL << 60;
const int MaxN = 5e4;

int T, cas;
int n;
int a[MaxN + 5];
struct Segtree
{
int l, r;
int sum;
}tree[4 * MaxN + 5];

void Build(int root, int l, int r)
{
tree[root].l = l, tree[root].r = r;
if(l == r) {
tree[root].sum = a[l];
return;
}
int mid = (l + r) >> 1;
Build(root << 1, l, mid);   //递归建树
Build(root << 1 | 1, mid + 1, r);
tree[root].sum = tree[root << 1].sum + tree[root << 1 | 1].sum;
}

void update(int root, int pos, int val) //更新操作
{
if(tree[root].l == tree[root].r) {
tree[root].sum = val;
return ;
}
int mid = (tree[root].l + tree[root].r) >> 1;
if(pos <= mid)
update(root << 1, pos, val); //更新左儿子
else
update(root << 1 | 1, pos, val);  //更新右儿子
tree[root].sum = tree[root << 1].sum + tree[root << 1 | 1].sum;
//更新完毕后更新区间和
}

int query(int root, int L, int R)  //查询
{
if(L <= tree[root].l && R >= tree[root].r)
return tree[root].sum;
int res = 0;
int mid = (tree[root].l + tree[root].r) >> 1;
if(mid >= L) res += query(root << 1, L, R);
if(mid < R) res += query(root << 1 | 1, L, R);
return res;
}

int main()
{
scanf("%d", &T);
cas = 0;
while(T--) {
cas++;
scanf("%d", &n);
for(int i = 1; i <= n; i++) {
scanf("%d", &a[i]);
}
printf("Case %d:\n", cas);
Build(1, 1, n);
char s[8];
while(scanf("%s", s) ) {
if(s[0] == 'E') break;
else if(s[0] == 'A') {
int p, val;
scanf("%d %d", &p, &val);
a[p] += val;
update(1, p, a[p]); //单点修改
}
else if(s[0] == 'S') {
int p, val;
scanf("%d %d", &p, &val);
a[p] -= val;
update(1, p, a[p]); //单点修改
}
else if(s[0] == 'Q') {
int l, r;
scanf("%d %d", &l, &r);
int ans = query(1, l, r); //询问区间[l, r]的和
printf("%d\n", ans);
}
}
memset(tree, 0, sizeof(tree));
}
return 0;
}

#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <algorithm>
using namespace std;
const int MaxN = 1e4;

int T, n;
int t;
int a[5 * MaxN + 5];
int c[5 * MaxN + 5];
char s[10];
int lowbit(int x)
{
return x & (-x);
}
void add(int x, int val)
{
while(x <= n)
{
c[x] += val;
x += lowbit(x);
}
}
int query(int end)
{
int sum = 0;
while(end > 0)
{
sum += c[end];
end = end - lowbit(end);
}
return sum;
}
int main()
{
t = 0;
scanf("%d", &T);
while(T--)
{
scanf("%d", &n);
for(int i = 1; i <= n; i++)
{
scanf("%d", &a[i]);
add(i, a[i]);
}
printf("Case %d:\n", ++t);
while(scanf("%s", s))
{
if(s[0] == 'E') break;
else if(s[0] == 'A')
{
getchar();
int x, val;
scanf("%d %d", &x, &val);
add(x, val);
}
else if(s[0] == 'Q')
{
getchar();
int l, r;
scanf("%d %d", &l, &r);
printf("%d\n", query(r) - query(l - 1));
}
else if(s[0] == 'S')
{
getchar();
int x, val;
scanf("%d %d", &x, &val);
add(x, -val);
}
}
memset(a, 0, sizeof(a));
memset(c, 0, sizeof(c));
}
return 0;
}