Line Segment tree --- hdu1754 I hate it

This is also the basic question of the Line Segment tree. With the foundation of the previous question, it is easier to do this question. It is basically the same. That is the sum. This is changed to the maximum value, basically, the idea is similar. below is the code implementation

 1 #include <cstdio> 2 #include <cstring> 3 #include <algorithm> 4  5 using namespace std; 6  7 const int MAX = 200010 * 4; 8 int segment[MAX]; 9 //向上调整10 void pushUp(int root)11 {12     segment[root] = max(segment[root * 2], segment[root * 2 + 1]);13 }14 15 void buildTree(int root, int left, int right)16 {17     if(left == right)18     {19         scanf("%d", &segment[root]);20         return;21     }22     int mid = (left + right) / 2;23     buildTree(root * 2, left, mid);24     buildTree(root * 2 + 1, mid + 1, right);25     //要把跟他上面所有关联的节点都要更新26     pushUp(root);27 }28 //更新节点29 void update(int root, int pos, int update_num, int left, int right)30 {31     if(left == right)32     {33         segment[root] = update_num;34         return;35     }36     int mid = (left + right) / 2;37     if(pos <= mid)38     {39         update(root * 2, pos, update_num, left, mid);40     }41     else42     {43         update(root * 2 + 1, pos, update_num, mid + 1, right);44     }45     pushUp(root);46 }47 //left和right为要查找的区间，L和R为当前查到了哪个区间48 int getMax(int root, int left, int right, int L, int R)49 {50     if(L == left && R == right)51     {52         return segment[root];53     }54     int mid = (left + right) / 2;55     int Max_Num = 0;56     if(R <= mid)57     {58         Max_Num = getMax(root * 2, left, mid, L, R);59     }60     else if(L > mid)61     {62         Max_Num = getMax(root * 2 + 1, mid + 1, right, L, R);63     }64     else65     {66         Max_Num = getMax(root * 2, left, mid, L, mid);67         Max_Num = max(Max_Num, getMax(root * 2 + 1, mid + 1, right, mid + 1, R));68     }69     return Max_Num;70 }71 72 int main()73 {74     int N, M;75     while(~scanf("%d %d", &N, &M))76     {77         memset(segment, 0, sizeof(segment));78         buildTree(1, 1, N);79         char ch;80         int t1, t2;81         for(int i = 0; i < M; i++)82         {83             getchar();84             scanf("%c %d %d", &ch, &t1, &t2);85             if(ch == ‘U‘)86             {87                 update(1, t1, t2, 1, N);88             }89             else90             {91                 printf("%d\n", getMax(1, 1, N, t1, t2));92             }93         }94     }95     return 0;96 }

 

Line Segment tree --- hdu1754 I hate it