题意：区间更新，区间求和
解题思路：本来以为自己搞出了区间更新A这题很简单呢，没想到这里面还有这么多学问，不过幸好坚持没有看解题报告和代码，自己对线段树的理解又更深了一层！主要是向下更新的时候有问题，自己调试的时候又出现了一个非常sb的常识性错误，然后就wrong到现在，主要的解题思路还是线段树的区间操作
解题代码：
1 #include <stdio.h> 2 #include <string.h> 3 #include <stdlib.h> 4 #define MAXN 200005 5 struct node 6 { 7 long long left ,right,mid; 8 long long num ; 9 long long cover; 10 } tree[MAXN*4]; 11 long long a[MAXN]; 12 long long L(long long c) 13 { 14 return 2*c; 15 } 16 long long R(long long c) 17 { 18 return 2*c + 1; 19 } 20 void up(long long c) 21 { 22 tree[c].num = tree[L(c)].num + tree[R(c)].num; 23 } 24 void build(long long c, long long p ,long long v ) 25 { 26 tree[c].left = p ; 27 tree[c].right = v; 28 tree[c].mid = (p + v)/2; 29 tree[c].num =0 ; 30 tree[c].cover = 0 ; 31 if(p == v ) 32 { 33 tree[c].num = a[p]; 34 return ; 35 } 36 build(L(c),p,tree[c].mid); 37 build(R(c),tree[c].mid +1,v); 38 up(c); 39 } 40 41 void update(long long c, long long p , long long v , long long value) 42 { 43 if(p <= tree[c].left && v >= tree[c].right) 44 { 45 tree[c].num = tree[c].num + (tree[c].right - tree[c].left +1) * value; 46 tree[c].cover =tree[c].cover +value ; 47 return; 48 } 49 if(tree[c].cover != 0 ) 50 { 51 tree[L(c)].cover = tree[L(c)].cover + tree[c].cover; 52 tree[L(c)].num = tree[L(c)].num + (tree[L(c)].right - tree[L(c)].left +1) * tree[c].cover; 53 tree[R(c)].cover =tree[R(c)].cover + tree[c].cover; 54 tree[R(c)].num = tree[R(c)].num +(tree[R(c)].right - tree[R(c)].left + 1)* tree[c].cover ; 55 tree[c].cover = 0 ; 56 } 57 if(v <= tree[c].mid ) update(L(c),p,v,value); 58 else if(p > tree[c].mid) update(R(c),p,v,value); 59 else 60 { 61 update(L(c),p,tree[c].mid,value); 62 update(R(c),tree[c].mid+ 1, v , value); 63 } 64 up(c); 65 66 } 67 68 long long tsum = 0 ; 69 void getsum(long long c, long long p ,long long v ) 70 { 71 if(p <= tree[c].left && v >= tree[c].right) 72 { 73 tsum += tree[c].num; 74 return; 75 } 76 if(tree[c].cover != 0 ) 77 { 78 tree[L(c)].cover = tree[L(c)].cover + tree[c].cover; 79 tree[L(c)].num = tree[L(c)].num + (tree[L(c)].right - tree[L(c)].left +1) * tree[c].cover; 80 tree[R(c)].cover =tree[R(c)].cover + tree[c].cover; 81 tree[R(c)].num = tree[R(c)].num +(tree[R(c)].right - tree[R(c)].left + 1)* tree[c].cover ; 82 tree[c].cover = 0 ; 83 } 84 if(v <= tree[c].mid) getsum(L(c),p,v); 85 else if(p > tree[c].mid) getsum(R(c),p,v); 86 else 87 { 88 getsum(L(c),p,tree[c].mid); 89 getsum(R(c),tree[c].mid +1 ,v ); 90 } 91 92 93 } 94 int main() 95 { 96 long long n ,m; 97 while(scanf("%I64d %I64d",&n,&m) != EOF) 98 { 99 100 for (long long i = 1;i <= n;i ++) 101 scanf("%I64d",&a[i]); 102 build(1,1,n); 103 char str[10]; 104 for(long long i =1 ;i <= m;i ++) 105 { 106 long long a, b ,c; 107 scanf("%s",str); 108 if(str[0] == 'Q') 109 { 110 scanf("%I64d %I64d",&a,&b); 111 tsum = 0 ; 112 getsum(1,a,b); 113 printf("%I64d ",tsum); 114 } 115 else 116 { 117 scanf("%I64d %I64d %I64d",&a,&b,&c); 118 update(1,a,b,c); 119 } 120 121 122 } 123 } 124 return 0 ; 125 }