1 #include <stdio.h> 2 #include <iostream> 3 using namespace std; 4 const int cmax = 100005; 5 const int minnum = -999999999; 6 int ans , s , x , posx , posy ; 7 struct Tnode 8 { 9 10 int maxs , sum , maxl , maxr ; // maxs为当前区间最大的序列和 ， sum为当前区间的和 ， maxl为当前区间左端点开始的最大序列和 ， maxr 11 //为当前空间右端点结束的最大序列和 12 int posi , posj , posl , posr ; //posi为maxs的左端点 ， posj为maxs的右端点 ， posl为 maxl的右端点 ， posr为maxr的左端点 13 int right , left ;//区间左端点 ， 区间右端点 14 }tree[cmax * 4]; 15 int temp , count = 0; 16 //从线段树的子节点往根节点更新信息 17 void PushUP(int p) { 18 tree[p].sum = tree[ 2 * p ].sum + tree[ 2* p + 1].sum; 19 tree[p].maxl = tree[ 2 * p ].maxl ; 20 tree[p].maxr = tree[ 2* p + 1] .maxr ; 21 tree[p].posl = tree[ 2* p].posl; 22 tree[p].posr = tree[ 2 * p + 1].posr; 23 int temp_sum; 24 temp_sum = tree[ 2* p ].sum + tree[ 2 * p + 1].maxl; 25 if ( temp_sum > tree[p].maxl ) 26 { 27 tree[p].maxl = temp_sum; 28 tree[p].posl = tree[ 2 * p + 1 ] .posl; 29 } 30 temp_sum = tree[ 2 * p + 1].sum + tree[ 2 * p ].maxr ; 31 if ( temp_sum >= tree[p].maxr ) 32 { 33 tree[p].maxr = temp_sum; 34 tree[p].posr = tree[ 2 * p ].posr; 35 } 36 tree[p].maxs = tree[ 2 * p ].maxs; 37 tree[p].posi = tree[ 2 * p].posi; 38 tree[p].posj = tree[ 2 * p].posj; 39 temp_sum = tree[ 2 * p].maxr + tree[ 2 * p +1 ].maxl; 40 41 if(temp_sum > tree[p].maxs || ( temp_sum == tree[p].maxs && tree[p*2].posr < tree[p].posi ) ) 42 { 43 tree[p].maxs= temp_sum ; 44 tree[p].posi=tree[p*2].posr ; 45 tree[p].posj=tree[p*2+1].posl ; 46 } 47 if ( tree[p].maxs < tree[ 2 * p + 1].maxs ) 48 { 49 tree[p].maxs = tree[ 2 * p + 1].maxs; 50 tree[p].posi = tree[ 2 * p + 1].posi; 51 tree[p].posj = tree[ 2 * p + 1].posj; 52 } 53 } 54 //建立线段树 ， 初始化 55 void build( int p , int L , int R) 56 { 57 if ( L == R ) 58 { 59 scanf("%d" , &temp); 60 tree[p].maxl = tree[p].maxr = tree[p].maxs = tree[p].sum = temp; 61 count++; 62 tree[p].posi = tree[p].posj = tree[p].posl = tree[p].posr = count; 63 tree[p].right = tree[p].left = L; 64 return ; 65 } 66 int mid = ( L + R ) /2 ; 67 build( p*2 , L , mid ); 68 build( 2* p +1 , mid + 1 , R); 69 tree[p].right = R; 70 tree[p].left = L; 71 PushUP(p);//从叶子往父节点更新值 ， 递归地从底层往上更新值 72 73 } 74 //线段树的查询操作 75 void query( int p , int L , int R) 76 { 77 if ( tree[p].left == L && tree[p].right == R) 78 { 79 if ( s + tree[p].maxl > ans ) 80 { 81 ans = s + tree[p].maxl; 82 posx = x; 83 posy = tree[p].posl; 84 } 85 86 if ( tree[p].maxs > ans ) 87 { 88 ans = tree[p].maxs; 89 posx= tree[p].posi; 90 posy = tree[p].posj; 91 92 } 93 int temp; 94 temp = s + tree[p].sum; 95 if ( temp > tree[p].maxr) 96 { 97 s = temp; 98 } 99 else100 {101 s = tree[p].maxr;102 x = tree[p].posr;103 }104 return ;105 }106 107 int mid = ( tree[p].left + tree[p].right) / 2 ;108 if ( R <= mid )109 {110 query( 2 * p , L , R);111 }112 else if ( L > mid )113 {114 query( 2 * p + 1 , L , R );115 }116 else117 {118 query( 2 * p , L , mid );119 query( 2 * p + 1 , mid + 1 , R );120 }121 }122 int main()123 {124 int n , m , value ;125 int a , b;126 scanf( "%d%d" , &n , &m);127 build( 1 ,1 , n );128 // cout << tree[6].maxs << tree[7].maxs << tree[8].maxs << tree[9].maxs;129 // cout << tree[1].maxs << tree[2].maxs << tree[7].maxs;130 while ( m --)131 {132 scanf("%d%d" , &a , &b );133 s = 0 ;134 x = a;135 ans = minnum;136 query( 1 , a , b );137 printf("%d %d %d\n",posx,posy,ans);138 }139 return 0 ;140 }
来源：https://www.cnblogs.com/lzhenf/archive/2011/12/15/2288583.html