数组写线段树，HDU1754

开始用链表写，可是申请空间导致无限MLE，蛋疼的无以复加

懒得写，默默剽窃个，自己写了注释

#include <stdio.h> 
typedef struct
{
    int left,right,max;
    int lChild,rChild;
}SegTree;
SegTree list[800000];// 
int max(int a, int b)//求最大 
{
    return a > b? a:b;
}
void createSegTree(int root, int left, int right)
{
    int mid;
    if(right < left)//不在该区间 
        return;
    list[root].left = left;
    list[root].right = right;
    list[root].max = 0;
    mid = (left + right) / 2;
    if(right - left >= 1)//在区间内，但未找到 
    {
        list[root].lChild = root << 1;//左移按二进制进行翻倍 
        list[root].rChild = (root << 1) + 1;
        createSegTree(list[root].lChild, left, mid);
        createSegTree(list[root].rChild, mid + 1, right);
    } 
    else{//找到了，将其孩子标志位-1 
        list[root].lChild = -1;
        list[root].rChild = -1;
    }
}

void updateSegTree(int root, int updateNum, int score)
{
    int mid;
    mid = (list[root].left + list[root].right) / 2;//用于判断左右 
    if(list[root].left <= updateNum && updateNum <= list[root].right)//位于区间内 
    {
        list[root].max = max(list[root].max, score);
        if(list[root].lChild != -1 && updateNum <= mid)
            updateSegTree(list[root].lChild, updateNum, score);//查找左子树 
        else if(list[root].rChild != -1 && updateNum >= mid + 1)
            updateSegTree(list[root].rChild, updateNum, score); 
    }
}

int queryHighestScore(int root, int left, int right)
{
    int mid,ans;
    mid = (list[root].left + list[root].right) / 2;//算法类似于查询 
    if(list[root].left == left && list[root].right == right)
        return list[root].max;
    else if(list[root].lChild != -1 && right <= mid)
        ans = queryHighestScore(list[root].lChild, left, right);
    else if(list[root].rChild != -1 && left >= mid + 1)
        ans = queryHighestScore(list[root].rChild, left, right);
    else{
        ans = queryHighestScore(list[root].lChild,left, mid);
        ans = max(ans, queryHighestScore(list[root].rChild, mid + 1, right));
    }
    return ans;
}

int main ()
{
    char order;
    int i,N,M,score,left,right,root;
//    freopen("in.txt","r",stdin);
    while(~scanf("%d%d",&N,&M))
    {
        root = 1;
        createSegTree(root,1,N);
        for(i = 1; i <= N; i++)
        {
            scanf("%d",&score);
            updateSegTree(root, i, score);
        }
        getchar();
        for(i = 0; i < M; i++)
        {
            scanf("%c%d%d",&order,&left,&right);
            getchar();
            if(order == 'Q')
                printf("%d
",queryHighestScore(root, left, right));
            else
                updateSegTree(root, left, right);
        }
    }
    return 0;
}