hdu1166 敌兵布阵

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http://acm.hdu.edu.cn/showproblem.php?pid=1166

这又是一道线段树的题目，，这是我做的第2道了

慢慢的懂得了一点线段树的只是了。。。。

我的代码：

#include <iostream>#include<cstdio>#include<cstring>using namespace std;#define maxn 500004struct node{    int left,right;    int num;};node tree[3*maxn];int out=0;void build(int left,int right,int i){    tree[i].left =left;    tree[i].right =right;    tree[i].num =0;    if(tree[i].left ==tree[i].right )        return ;    build(left,(left+right)/2,2*i);    build((left+right)/2+1,right,2*i+1);}void insert(int id,int i,int j)//i营地增加j个人{    if(tree[id].left<=i&&tree[id].right >=i)        tree[id].num +=j;    if(i>tree[id].right||i<tree[id].left )        return;    int mid=(tree[id].left +tree[id].right )/2;    if(i<=mid)        insert(id*2,i,j);    else        insert(id*2+1,i,j);}void sum(int id,int i,int j)  //问从i营地到j营地有多少人。。。{    int mid=(tree[id].left +tree[id].right )/2;    if(tree[id].left ==i&&tree[id].right ==j)    {        out+=tree[id].num ;        return;    }    if(j<=mid)        sum(2*id,i,j);    else if(i>mid)        sum(2*id+1,i,j);    else     {        sum(2*id,i,mid);        sum(2*id+1,mid+1,j);    }}int main(){    int t,n,num,l,r,Case=1;    scanf("%d",&t);    while(t--)    {        printf("Case %d:\n",Case++);        scanf("%d",&n);        build(1,n,1);        for(int i=1;i<=n;i++)        {            scanf("%d",&num);            insert(1,i,num);        }        char ss[20];        while(scanf("%s",ss))        {            if(ss[0]=='E')                break;            if(ss[0]=='Q')            {                scanf("%d%d",&l,&r);                sum(1,l,r);                printf("%d\n",out);                out=0;            }            if(ss[0]=='A')            {                scanf("%d%d",&l,&r);                insert(1,l,r);            }            if(ss[0]=='S')            {                scanf("%d%d",&l,&r);                insert(1,l,-r);            }        }    }    return 0;}

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