HDU - 1166 敌兵布阵 （线段树---点修改）

题意：

1、Add i j,i和j为正整数,表示第i个营地增加j个人（j不超过30） 
2、Sub i j ,i和j为正整数,表示第i个营地减少j个人（j不超过30）; 
3、Query i j ,i和j为正整数,i<=j，表示询问第i到第j个营地的总人数; 
4、End 表示结束，这条命令在每组数据最后出现。

#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<cctype>
#include<cmath>
#include<iostream>
#include<sstream>
#include<iterator>
#include<algorithm>
#include<string>
#include<vector>
#include<set>
#include<map>
#include<stack>
#include<deque>
#include<queue>
#include<list>
#define lowbit(x) (x & (-x))
const double eps = 1e-8;
inline int dcmp(double a, double b){
    if(fabs(a - b) < eps) return 0;
    return a > b ? 1 : -1;
}
typedef long long LL;
typedef unsigned long long ULL;
const int INT_INF = 0x3f3f3f3f;
const int INT_M_INF = 0x7f7f7f7f;
const LL LL_INF = 0x3f3f3f3f3f3f3f3f;
const LL LL_M_INF = 0x7f7f7f7f7f7f7f7f;
const int dr[] = {0, 0, -1, 1, -1, -1, 1, 1};
const int dc[] = {-1, 1, 0, 0, -1, 1, -1, 1};
const int MOD = 1e9 + 7;
const double pi = acos(-1.0);
const int MAXN = 50000 + 10;
const int MAXT = 10000 + 10;
using namespace std;
int a[MAXN];
int sum[MAXN << 2];
char s[10];
void build(int id, int L, int R){
    if(L == R){
        sum[id] = a[L];
    }
    else{
        int mid = L + (R - L) / 2;
        build(id << 1, L, mid);
        build(id << 1 | 1, mid + 1, R);
        sum[id] = sum[id << 1] + sum[id << 1 | 1];
    }
}
void update(int k, int id, int L, int R, int v){
    if(L == R){
        sum[id] += v;
    }
    else{
        int mid = L + (R - L) / 2;
        if(k <= mid) update(k, id << 1, L, mid, v);
        else update(k, id << 1 | 1, mid + 1, R, v);
        sum[id] = sum[id << 1] + sum[id << 1 | 1];
    }
}
int query(int l, int r, int id, int L, int R){
    if(l <= L && R <= r){
        return sum[id];
    }
    int mid = L + (R - L) / 2;
    int ans = 0;
    if(l <= mid) ans += query(l, r, id << 1, L, mid);
    if(r > mid) ans += query(l, r, id << 1 | 1, mid + 1, R);
    return ans;
}
int main(){
    int T;
    scanf("%d", &T);
    int kase = 0;
    while(T--){
        memset(a, 0, sizeof a);
        memset(sum, 0, sizeof sum);
        int N;
        scanf("%d", &N);
        for(int i = 1; i <= N; ++i){
            scanf("%d", &a[i]);
        }
        build(1, 1, N);
        printf("Case %d:\n", ++kase);
        while(scanf("%s", s) == 1){
            if(s[0] == 'E') break;
            int i, j;
            scanf("%d%d", &i, &j);
            if(s[0] == 'A'){
                update(i, 1, 1, N, j);
            }
            else if(s[0] == 'S'){
                update(i, 1, 1, N, -j);
            }
            else{
                printf("%d\n", query(i, j, 1, 1, N));
            }
        }
    }
    return 0;
}